Tuesday

September 30, 2014

September 30, 2014

Posted by **Megan** on Thursday, August 27, 2009 at 10:31am.

cos2x=(*2/2)

- MEGAN !! Pre Calc -
**Reiny**, Thursday, August 27, 2009 at 12:20pmMegan, look at how your post came out.

what is *2/2 supposed to be?

I have a feeling you mean √2/2

If so, then

since the cosine is positive in quadrants I and IV

2x = 45º or 2x = 315º

then x = 22.5º or x = 157.5º

but we know that the period of cos(2x) is 180º, so by adding 180 to each of our answers we get the other solutions in the given domain, or

x = 202.5º

x = 337.5º

just noticed that you probably wanted the solutions in radians, that would be

pi/8, 7pi/8, 9pi/8, and 15pi/8

**Answer this Question**

**Related Questions**

Pre Calc - Solve the equation on the interval [0,2pi). cos2x=(*2/2)

Pre-Calculus - Find all solutions to the equation in the interval [0, 2pi) cos4x...

Pre-Calc/Math - Given cos x=2/3 and 3pi/2<x<2pi, find the exact value of ...

PRE CALC PLEASE HELP!!!!!!!! - find the solutions of the equation that are in ...

pre calc - cos2x=cosx in interval of [0,2pie]

Precalculus - Please help!!!!!!!!!!! Find all solutions to the equation in the ...

calculus - Solve for x on the interval (0, 2pi] (sin2x + cos2x)^2 = 1

Math - Can I please get some help on these questions: 1. How many solutions does...

Pre-Calc/Math - Use factoring, the quadratic formula, or identities to solve cos...

Pre-calc - The question is solve for cosx= 0.60 on the interval [0,2pi). The ...