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23-590: Ballona Lagoon “runs for about a mile, parallel to Via Marina in Marina Del Rey.” The primary wetland is bounded by Pacific Avenue, Via Dolce, Hurricane Street, and Yawl Street. At Hurricane the channel makes a sharp turn and becomes the Grand Canal of the Venice Canals. When it reaches Venice Boulevard the water disappears into an underground storm drain. Part of the historic Ballona Valley ecosystem/watershed,

46-515: A semicircle (with a vertex on the semicircle and its defining rays going through the endpoints of the semicircle) is a right angle. Two application examples in which the right angle and the Thales' theorem are included (see animations). The solid angle subtended by an octant of a sphere (the spherical triangle with three right angles) equals π /2  sr . California brittlebush Encelia conspersa A.Gray Encelia californica

69-527: A proof as well but using a more explicit assumption. In Hilbert 's axiomatization of geometry this statement is given as a theorem, but only after much groundwork. One may argue that, even if postulate 4 can be proven from the preceding ones, in the order that Euclid presents his material it is necessary to include it since without it postulate 5, which uses the right angle as a unit of measure, makes no sense. A right angle may be expressed in different units: Throughout history, carpenters and masons have known

92-463: A quarter turn . If a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles. The term is a calque of Latin angulus rectus ; here rectus means "upright", referring to the vertical perpendicular to a horizontal base line. Closely related and important geometrical concepts are perpendicular lines, meaning lines that form right angles at their point of intersection, and orthogonality , which

115-535: A quick way to confirm if an angle is a true right angle. It is based on the Pythagorean triple (3, 4, 5) and the rule of 3-4-5. From the angle in question, running a straight line along one side exactly three units in length, and along the second side exactly four units in length, will create a hypotenuse (the longer line opposite the right angle that connects the two measured endpoints) of exactly five units in length. Thales' theorem states that an angle inscribed in

138-465: A right angle) and obtuse angles (those greater than a right angle). Two angles are called complementary if their sum is a right angle. Book 1 Postulate 4 states that all right angles are equal, which allows Euclid to use a right angle as a unit to measure other angles with. Euclid's commentator Proclus gave a proof of this postulate using the previous postulates, but it may be argued that this proof makes use of some hidden assumptions. Saccheri gave

161-613: A right angle. Right angles are fundamental in Euclid's Elements . They are defined in Book 1, definition 10, which also defines perpendicular lines. Definition 10 does not use numerical degree measurements but rather touches at the very heart of what a right angle is, namely two straight lines intersecting to form two equal and adjacent angles. The straight lines which form right angles are called perpendicular. Euclid uses right angles in definitions 11 and 12 to define acute angles (those smaller than

184-732: Is a quadrilateral with four right angles. A square has four right angles, in addition to equal-length sides. The Pythagorean theorem states how to determine when a triangle is a right triangle . In Unicode , the symbol for a right angle is U+221F ∟ RIGHT ANGLE ( ∟ ). It should not be confused with the similarly shaped symbol U+231E ⌞ BOTTOM LEFT CORNER ( ⌞, ⌞ ). Related symbols are U+22BE ⊾ RIGHT ANGLE WITH ARC ( ⊾ ), U+299C ⦜ RIGHT ANGLE VARIANT WITH SQUARE ( ⦜ ), and U+299D ⦝ MEASURED RIGHT ANGLE WITH DOT ( ⦝ ). In diagrams,

207-448: Is a species of flowering plant in the family Asteraceae known by the common name California brittlebush . It is also commonly referred to as California coast sunflower and California bush sunflower . This shrub is native to southern California (U.S.) and northern Baja California (México). It is a member of the coastal sage plant community at the shoreline, and the chaparral and woodlands plant community on inland foothills in

230-459: Is an achene 5 to 7 millimeters long, with no pappus . It blooms from February to June, and attracts butterflies, bees, and other insects. It is a host plant for the larvae of the Bay checkerspot butterfly , a threatened species. Encelia californica is cultivated by specialty nurseries as an ornamental plant , for use in native plant and wildlife gardens , and natural landscaping projects. It

253-578: Is now dry land as a result of filling and development and natural conditions.” The tide gates replace as much as 95 percent of the lagoon’s water daily. The Lighthouse Street Bridge crossing the lagoon is a closed-spandrel bridge limited to pedestrian and bicycle traffic only. The bridge, sometimes called the Ballona Lagoon Bridge , was built by Abbot Kinney as part of his Venice of California development. The city of Los Angeles has recommended applying for Historic-Cultural Monument status for

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276-438: Is separated from the ocean by a strand or bar of beach sand. Its entire length lies within 1,000 yards (910 m) of the ocean. It connects to the Venice Canals to the northwest and to the ocean channel entrance to Marina Del Rey on the southeast. Historically, the name Ballona Lagoon referred to a much larger area than that covered by the property here involved and was part of what was once Rancho Ballona . That additional area

299-488: Is the property of forming right angles, usually applied to vectors . The presence of a right angle in a triangle is the defining factor for right triangles , making the right angle basic to trigonometry. The meaning of right in right angle possibly refers to the Latin adjective rectus 'erect, straight, upright, perpendicular'. A Greek equivalent is orthos 'straight; perpendicular' (see orthogonality ). A rectangle

322-499: The Transverse and Peninsular Ranges . Encelia californica is a bushy shrub that reaches between 50–150  cm (20-60 inches) in height. It has many thin branches covered in widely spaced green leaves which are a rounded diamond shape. The solitary flower heads are daisy like, with 15 to 25 bright yellow ray florets 1 to 3 centimeters long around a center of protruding yellowish to purplish brown disc florets . The fruit

345-458: The adjacent beach is a protected nesting site for the California least tern , which also make appearances in the lagoon. Fish present in the lagoon include goby , halibut and topsmelt silverside . The Lagoon is accessible via the 1.8-mile (2.9 km) Ballona Lagoon Marine Preserve Trail, said to be "fragrant with coastal sage and jasmine, and if you run south, you can turn right at the base of

368-469: The bodies of water now called Ballona Lagoon and Del Rey Lagoon are separated sisters, kept apart since the 1960s by the construction of the Marina Del Rey boat channel. Prior to the dredging of the sailboat harbor, “this acreage was for centuries a salt marsh .” As described in a 1981 legal filing: The Lagoon in its present configuration is a narrow elongated area covered by very shallow water and

391-589: The bridge. The Silver Strand development that fronts the lagoon “got its name and was subdivided in 1906 by Kinney, who built the Venice canals , which feed into the Ballona Lagoon. But it remained a subdivision on paper, and development became even less of a priority when oil was discovered in the area in 1930. For nearly 40 years, the Strand was a forest of oil pumps and wells.” There are no past or present lighthouses in

414-468: The fact that an angle is a right angle is usually expressed by adding a small right angle that forms a square with the angle in the diagram, as seen in the diagram of a right triangle (in British English, a right-angled triangle) to the right. The symbol for a measured angle, an arc, with a dot, is used in some European countries, including German-speaking countries and Poland, as an alternative symbol for

437-488: The lagoon and run out onto the jetty that is the northern bank of the Marina del Rey channel." Right angle Right Interior Exterior Adjacent Vertical Complementary Supplementary Dihedral In geometry and trigonometry , a right angle is an angle of exactly 90 degrees or ⁠ π {\displaystyle \pi } / 2 ⁠ radians corresponding to

460-433: The pre-development ecology of the area, dredging six feet (1.8 m) down at the tidal inlet to create fish spawning habitat, and building an island for nesting birds. Silt, litter and remnants of 50-year-old oil drilling equipment were removed. Further refurbishment took place in 2011, when the city added dog fencing, stabilized the banks of the waterway, and reseeded the rare wildflower called Orcutt’s yellow pincushion . At

483-536: The time of a 1987 attempt to redevelop the Lagoon area, including potentially removing the Lighthouse Street Bridge, “Much of the ensuing debate revolved around the question of whether the lagoon is a beautiful, rare habitat for wildlife or a stinking mud hole.” A local marine biology professor spoke in defense of the mud, as it plays host to the “worms, clams and snails that live in the lagoon” which in turn feed

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506-421: The vicinity of Lighthouse Street; the street names in this neighborhood are nautical terms in alphabetical order from Anchorage to Yawl. The lagoon was restored incrementally beginning in 1988, with major work 1996-1997 after the city purchased “Lot R” (which comprised two-thirds of the lagoon) from a private owner. Improvements included viewing platforms, fencing, signage, native California plants authentic to

529-810: The “ avocets , curlews and sandpipers .” One homeowner advocating for more development commented, “It is very charming at high tide but at low tide it smells.” The restoration has been described as “wildly successful, providing rich native habitat and regulated access for people, where degraded land once dominated.” Common native plants of the Lagoon include coastal buckwheat , beach-sand verbena , pickleweed , big saltbush , California brittlebush , and lemonade berry . Common wildlife includes snowy egrets , great blue herons , cormorants , kingfishers , mergansers , coots , horn snails , fiddler crabs , hermit crabs , California mussels , three colors of sea anemones , chitons , limpets , volcano barnacles , innkeeper worms , and sea hares . A fenced-off lot on

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