CK12 - Geometry

To find theseratios,identifythe sidesadjacentto eachangleand the hypotenuse.Rememberthat an adjacent
side is the one that doescreatethe angleand is not the hypotenuse.

So, the cosineof is about and the cosineof is about.

Notethat is NOTone of the specialright triangles,but it is a right trianglewhosesidesare a
Pythagoreantriple.

Sinesand Cosinesof SpecialRightTriangles

It may help you to learnsomeof the mostcommonvaluesfor sine and cosineratios.The tablebelowshows
you valuesfor anglesin specialright triangles.

Sine

Cosine

You can use theseratiosto identifyanglesin a triangle.Work backwardsfrom the ratio.If the ratio equals
one of thesevalues,you can identifythe measurementof the angle.

Example 4

Whatis the measureof in the trianglebelow?