Question

Which of the following have a solution:



cos 2x=-4

[sin(x/2)]^2 = - (2/3)

3tan 3x=5

None of the above.​

Answer 1

Answer:

using C-D formulae :

we get

2sin2xcosx−3sin2x=2cos2xcosx−3cos2x

(2cosx−3)sin2x=(2cosx−3)cos2x

cos2x=sin2x

tan2x=1

x=

2

nΠ

+

8

Π

Answer 2

Answer:

second one=[sin(x/2) ]²=-(2/3)