Question #98a5e

1 Answer
Mar 23, 2017

x={pi/4,(7*pi)/4}x={π4,7π4}

Explanation:

First subtract 16 from both sides and then divide both sides by 2 to get: cos^2(x)=1/2cos2(x)=12. Then square root both sides to get cos(x)=1/(sqrt(2))cos(x)=12. Cosine only equals this at angles pi/4π4 and (7*pi)/47π4 (within a range from 0 to 2*pi2π) so those two angles are our answers. Hope I helped!