http://www.ck12.org Chapter 8. Right Triangle Trigonometry
52 + 122 =h^2
13 =hSo, sinA=^1213 ,cosA= 135 , and tanA=^125.
Example B
Find the sine, cosine, and tangent of^6 B.
Find the length of the missing side.
AC^2 + 52 = 152
AC^2 = 200
AC= 10
√
2
Therefore, sinB=^10
√
2
15 =
2√
2
3 ,cosB=5
15 =1
3 , and tanB=10√
2
5 =^2
√
2.
Example C
Find the sine, cosine and tangent of 30◦.
This is a special right triangle, a 30-60-90 triangle. So, if the short leg is 6, then the long leg is 6
√
3 and the
hypotenuse is 12.
sin 30◦= 126 =^12 ,cos 30◦=^6
√
3
12 =
√
3
2 , and tan 30◦= 6
6√
3
= √^1
3
·
√
√^3
3
=
√
3
3.
Watch this video for help with the Examples above.