find the value of theta

Please answer clearly and explain the solution clearly and easy to understand. Thanks!
(guaranteed medal for a good answer)

Question

find the value of theta

Please answer clearly and explain the solution clearly and easy to understand. Thanks!
(guaranteed medal for a good answer)

moongazer · Answer

$$3\cos ^{2}\theta-7\cos \theta+4=0$$

anonymous · Answer

Let cos(x) = b

3b^2 - 7b + 4 = 0

Solve b

anonymous · Answer

WTF wikipedia?

anonymous · Answer

You should probably get four answers

moongazer · Answer

b=1, b=4/3

moongazer · Answer

$$0\le \theta \le 2 \pi$$

moongazer · Answer

could there be an undefined solution for the b=4/3

anonymous · Answer

cos theta = 1
theta = 0, 2pi

moongazer · Answer

because there is no cosine that has a value of 4/3 right?

moongazer · Answer

so that is the only answer?

anonymous · Answer

It's undefined because cos theta = Adjacent over hypotenuse
hypotenuse is never greater than the adjacent (leg)

anonymous · Answer

probably 
Remember to press good answer.

moongazer · Answer

so cos, sin and tan should never have a value greater than 1?

anonymous · Answer

For tan you can 
But not for cos or sin

moongazer · Answer

ohh i see because tan =y/x
Thanks!