Geometry 8-2Trigonometric Ratios

Vocabulary A trigonometric ratio is a ratio of two

sides of a right triangle.

1st Trigonometric Ratio The sine (sin):

oppositesin

hypotenuse

Examples Write each trig ratio.

sin J

sin K

2nd Trigonometric Ratio The cosine (cos):

adjacentcos

hypotenuse

Example Write each trig ratio.

cos B

cos A

3rd Trigonometric Ratio The tangent (tan):

oppositetan

adjacent

Example Write each trig ratio.

tan A

tan B

How to Remember SOHCAHTOA

Calculator You can use the calculator to evaluate

the ratio of an angle’s measure.

Make sure the calculator is in degrees!!!

sin(22°)= cos(46°)= tan(65°)=

Using Trig Ratios Example Find the measures of x and h.

h36 in.

60º

30º

x

24 ft

Another Example Find the length of side BC.

Word Problem You and your friends decide to build a

bike ramp using a 4 ft piece of wood. You make a 45° angle with the ground because it will give you the most distance after takeoff. How high above the ground will the back wheel be when your bike goes off the ramp?