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Lauren G.

asked • 08/07/17

Solve exactly on the interval [0, 2π). (Enter your answers as a comma-separated list.)

16 cos(2θ) = 16 cos^2(θ) − 9

2 Answers By Expert Tutors


Michael J. answered • 08/07/17

5 (5)

Effective High School STEM Tutor & CUNY Math Peer Leader

Doug C.

Actually there should be four roots on the interval from [0,2pi).
When taking the square root of 7/16 there are two values to consider +/- √7 / 4. 
Those values will yield x/theta values in the first and 2nd quadrants. There will be corresponding results in 3rd/4th quadrants, subtracting from 2pi. 


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