Transcript 6.2 Solving Trigonometric Equations with Identities

6.2 Solving Trigonometric
Equations with Identities
sin 2  2 cos   0
0    360o
• If you see a trig function of a double angle and
another trig function of a single angle, try
using the double angle formula.
cos 2  3sin   2
0    360o
4cos2   4sin   5  0
0    360o
• If you see two different trig functions and one
is being squared, try using a pythagorean
identity to get the equation in terms of one
trig function.
sin   cos  1
0    360o
• Try squaring both sides when the previous two
hints don’t apply. Because you can’t get sine in
terms of cosine, but you can get sine squared
in terms of cosine squared. Don’t forget to
check for extraneous solutions.
• Also, you can try using the ratio and reciprocal
identities (#5 on WS 6.2)