Posted by **tomas** on Tuesday, May 31, 2011 at 7:43pm.

verifying a solution.

4cos^2 2x-2=0

- trig -
**Reiny**, Tuesday, May 31, 2011 at 8:43pm
4cos^2 2x-2=0

cos^2 (2x) = 1/2

cos (2x) = ± 1/√2

2x = 45° or 2x = 135° or 2x = 225° or 2x = 315°

x = 22.5°, 67.5°, 112.5°, 157.5, ...

the period of cos 2x is 180°, so adding 180° to any of the above answers will produce a new answer.

So there is an infinite number of solutions.

## Answer This Question

## Related Questions

- pre cal verifying identities - how do I verify?? sin(x)+cos3(x)=sin(x)-3cos(x)+...
- trig - Write an equation for simple harmonic motion, given that the amplitude ...
- Trig - Im having serious issues with verifying Trig. identities. Please help! ...
- trig - y=4cos(3x-2(3.14))
- trig - 5sin(2x)+4cos(x)=0
- trig - 5sin(2x)+4cos(x)+0
- trig - 4cos(2x)+2cos(x)+3=0
- TRIG - Factor 4cos^2x+4cosx-1=0
- Trig - Factor 4cos^2x+4cosx-1=0
- HELPPPPPPP (TRIG) - 4cos(x) 5=6sec(x)

More Related Questions