Question

Find all the solutions for cosx cos(3x) - sinx sin(3x) = 0 ..on the interval [0,2pi]

Answer 1

i think pi/4, 3pi/4, 5pi/4 and 7pi/4 :)

Answer 2

use cos(A+B) formula

Answer 3

Thank you :3

Answer 4

welcome :)

Answer 5

those are not the correct answers

Answer 6

Would they be pi/8, 3pi/8, 5pi/8, 7pi/8, 9pi/8, 11pi/8, 13pi/8, 15pi/8?

Answer 7

@ganeshie8

Answer 8

cos(4x) = 0

4x = pi/2 + npi

x = pi/8 + npi/4

= pi/8, 3pi/8....

so yes !! good work !!!

Answer 9

Thank you ><" So much

Answer 10

np :)