Dylan's SHWEET Blog :)

8-5

In this section we learned about using identities to get get the same trig. func: if you can't, try to make it tan or cot by sin/cos or cos/sin.**

*You follow inverse rules for these problems.*

THINGS YOU CAN'T DO!!!-
1. divide by a trig. func. when solving to cancel
2. cancel from the inside of a trig. func.
EX:
sin(2x)/2 => you can't cancel the 2

sin 2x=sin x => you can't divide and cancel

Now for real problems:

2sin^2Θ-1=0 (if you get confused, replace the sin with a normal equation: 2x^2-1=0)
2sin^2Θ=1
√sin^2Θ=√1/2
sinΘ= +/- √1/2
Θ=45°, (now we have to find the other quadrants) 135°,225°, 315°
the angles are the answers

now for another:

2sinΘ= cosΘ
2(sinΘ/cosΘ)=1
2tanΘ=1
tanΘ=1/2
Θ=tan^-1(1/2) (inverse rules :D )
now to find the quadrants, I & III
Θ=26.565°, 206.565°

the end :)