Warm- Up1. Find the sine, cosine and

tangent of A.2. Find x.

12 x

51°

6

810

A

Find the trigonometric ratios.D

O G

5

12

13

sin D =

tan D =

cos D =

sin G =

tan G =

cos G =

Find the missing variables.

6 feet43.2°

x

y

12.9

25°

Finding an angle.(Figuring out which ratio to use and getting

to use the 2nd button and one of the trig buttons.)

Let A be an acute angle in a right triangle. Approximate the measure of A to the

nearest degreesinA=.36 cosA=.42

Let’s practice using the calculator!

2nd cos

.36

.42

sin 2nd

Ex. 1: Find . Round to four decimal places.

9

17.2

Make sure you are in degree mode (not radian).

9

2.17tan

2nd tan 17.2 9

3789.62

Ex. 2: Find . Round to three decimal places.

23

7

Make sure you are in degree mode (not radian).

23

7cos

2nd cos 7 23

281.72

Ex. 3: Find . Round to three decimal places.

400

200

Make sure you are in degree mode (not radian).

400

200sin

2nd sin 200 400

30

When we are trying to find a sidewe use sin, cos, or tan.

When we are trying to find an angle we use sin-1, cos-1, or tan-1.