(PWL 4.3 and4.8, AM 9-1)

Triangle Trigonometry is the way to find the length of a side or measurement of an angle of a right triangle. Using the formulas:

sin = length of opposite side / length of hypotenuse

csc = length of hypotenuse / length of opposite side

cos = length of adjacent side / length of hypotenuse

sec = length of hypotenuse / length of adjacent side

tan = length of opposite side / length of adjacent side

cot = length of adjacent side / length of opposite side

Angle of depression and angle of elevation are angles on a triangle. They equal the same measurement. It is theta and the top of the triangle.




Practice Problems:

1. The Vertex angle of an isosceles triangle measures 74º, and the base of the triangle is 16 inches. find the measures of the legs of the triangle and base triangles.

2. You are standing on top of PV and spot the courtyard bunny rabbits on the ground 40 feet from the base of the building. The roof is 100 feet above the ground. Find the measure of the angle of depression from you to the bunnies.

3. A rectangle has sides that are 8 and 12 inches long. Find the measures of the acute and obtuse angles formed by the intersection of the diagonals.

4. An isosceles trapezoid has sides whose lengths are 7, 23, 15, and 15 cm. Find the measures of both the upper and lower base angles of the trapezoid.


1. 13.29 in.

2. 68.5º

3. 112º, 68º

4. 58º, 122º