SOLUTION: I would love help with this problem. I am stuck. Use inverse trigonometric functions to find the solutions of the equation that are in the given interval, and approximate the s

Algebra ->  Trigonometry-basics -> SOLUTION: I would love help with this problem. I am stuck. Use inverse trigonometric functions to find the solutions of the equation that are in the given interval, and approximate the s      Log On


   

Question 970523: I would love help with this problem. I am stuck.
Use inverse trigonometric functions to find the solutions of the equation that are in the given interval, and approximate the solutions to
four decimal places.
cos^2x+2cosx−2=0; [0,2π)
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Use inverse trigonometric functions to find the solutions of the equation that are in the given interval, and approximate the solutions to
four decimal places.
cos^2x+2cosx−2=0; [0,2π)
Use quadratic formula to solve for cosx
cosx+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a=1, b=2, c=-2
ans:
cosx=-2.73 (reject,(-1 < cosx < 1))
or
cosx=0.732
x≈0.75, 5.53 (in quadrants I and IV where cos>0)