G.SRT.B.4: Prove theorems about triangles. Theorems include: a line parallel to one side of a triangle divides the other two proportionally, and conversely; the Pythagorean Theorem proved using triangle similarity.

Prove theorems about triangles. Theorems include: a line parallel to one side of a triangle divides the other two proportionally, and conversely; the Pythagorean Theorem proved using triangle similarity.

Example Problems

What are the angle measures in a triangle whose three sides each have a length of

1

unit? Explain.

A

26

‑foot ladder leans against a vertical wall. The base of the ladder is

10

feet from the wall.
How high up the wall does the ladder reach?

a. For which acute angles

a

is

\sin a = \cos a

? Explain.

b. For which acute angles

a

is

\sin a = \cos 2a

? Explain.

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