Question #1bd0f

1 Answer

#theta=30°#, #or theta = 150°#

Explanation:

#2sin^2theta-sintheta=0#

or, #sintheta(2sintheta-1)=0# [taking #sintheta# common from both sides]

now,either #sintheta=0# or #(2sintheta-1)=0#

we know the value of #sintheta# being #0# is #0# degree.so that rules out because the domain is #0 < theta < 360.#

now #(2sintheta-1)=0#

or #2sintheta=1#
so #sintheta=1/2#
the value of #sintheta# being #1/2# is #30# degree.

So the first value is #30#. This is in the first quadrant, but we know #sin theta# is positive in the second quadrant too. So we take #180# degrees. We can't take 90 degrees because that would change sin to cos. So now the equation is:

#sin30=sin(180-30)#

#sin30=sin150#

so this is the answer.

Answer: #sin30°#, #sin150°#