sin (x-10) = cos (2x+40),
find value of x when:
1. 2x+40 < 90
2. 2x+40 > 90

the first one is easy to figure out. i'll assume that (x-10) and (x-10) are complementary angles where (x-10) + (2x+40) = 90
so x is gonna be 20

however in the second case of the question ( 2x+40 > 90 ), the answer sheet says x = 40 where (x-10) + (2x+40) = 150

WHERE DID THE 150 COME FROM?