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Section 9-1. Solving Right Triangles. Solving a Triangle. In chapter 7 we defined the trigonometric functions in terms of coordinates of points on the circle. In this chapter, we will shift our emphasis to triangles. Solving a Triangle.
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Section 9-1 Solving Right Triangles
Solving a Triangle • In chapter 7 we defined the trigonometric functions in terms of coordinates of points on the circle. In this chapter, we will shift our emphasis to triangles.
Solving a Triangle • When certain parts (sides and angles) of a triangle are known, you can use trigonometric relationships to find the unknown parts. This is called solving the triangle.
Trigonometric Functions • The right triangles shown on p. 331 both have an acute angle of measure Θ and are similar. Therefore the lengths of the corresponding sides are proportional. hypotenuse opposite θ adjacent
Trigonometric Functions • This gives us the following equations:
OPP TAN= ADJ OPP SIN= HYP ADJ COS= HYP SohCahToa
Trigonometric Functions • By the reciprocal relationships we also have:
Example • In ∆ABC, A = 90°, a = 29 and b = 21. Find c, B and C.
Example • A rhombus with perimeter 40 cm has a 70° angle. Find the lengths of its diagonals.