precal 2

solve the equation 4cos^2x-1=0

1. 👍 0
2. 👎 0
3. 👁 105
1. cos^2x = 1/4
cosx = ± 1/2

do you know an angle x , so that cosx = 1/2 ???
and by the CAST rule, isn't that angle in any of the 4 quadrants?

hint: cos60° = 1/2

1. 👍 0
2. 👎 0
posted by Reiny

Similar Questions

1. pre cal 2

solve the equation 4cos^2x-1=0

asked by kc on July 24, 2011
2. pre calc

solve the equation 1+4sin(x)=4cos^2(x)

asked by bandit5571 on January 11, 2011
3. Trigonometry

Need help solving problems using the Trigonometric Identities: 8cos^4 thet=cos4theta+4cos2theta+3 I am a bit unsure how to solve it. I am aware that the first step I must take is to simplify the problem and then use the Product to

asked by sierra on April 23, 2007
4. trig

Write an equation for simple harmonic motion, given that the amplitude equals 4 inches and the period equals 2 seconds and the max displacement occurs when t=0. answers: y=4sin pi t, y=4cos pi t, y=4cos t, y=4sin2 pi t

asked by Kayla on May 17, 2012
5. Pre-Cal

Hi, can someone please solve this step-by-step for me? I really don't get it... Directions: Use the quadratic formula to solve the equation in the interval [0,2PI). Then use a graphing utility to approximate the angle x.

asked by james on January 1, 2010
6. Trig

Solve the equation for the given domain. 4cos^2 θ = 1 for 0 to 360 degrees. I get 60, 120, 240, and 300. Are these correct? If so, how would I represent them with some sort of expression?

asked by Anonymous on May 16, 2015
7. Calc III

Express the volume of the solid that the cylinder r = 4cos(theta) cuts out of the sphere of radius 4 centered at the origin with a triple integral in cylindrical coordinates. I have already found the intervals, but I cannot solve

asked by Anon on November 2, 2016
8. More trig

Use the Quadratic Formula to solve the equation in the interval [0,2pi). Then use a graphing utility to approximate the angle x. (1) 5/(tanx+secx) (2) 4cos^2x-4cosx-1=0 Thank you.

asked by Poindexter on November 17, 2008
9. pre-cal

What are the steps for solving this? Directions Use the quadratic formula to solve the equation in the interval [0,2PI). Then use a graphing utility to approximate the angle x. 4cos^2x-4cosx-1=0 thanks.

asked by james on January 1, 2010
10. Maths

a) Express f(theta) = 4cos theta - 6sin theta in the form r cos(theta + alpha) b) Hence find the general solution of the equation 4cos theta - 6sin theta =5 c) Hence, find the minimum value of the function 1/4+f( theta)

asked by Becky on April 23, 2019

More Similar Questions