Question

If cos x = sin(20 + x)° and 0° < x < 90°, the value of x is what?

Answer 1

Answer:

x=35°

Step-by-step explanation:

If cos x = sin(20 + x)° and 0° < x < 90°, the value of x is 35°.

Answer 2

we can change cos to sin by saying cosx=sin(90-x)

now we drop sin and make the angles equal (nothing needs to be added or subtracted since its in the first quadrant)

90-x=20+x+k.360.......kEZ (k is an element of set of integers) (we say k.360 if it's cos and sin and k.180 if it's tan)

-x-x=20-90+k.360........kEZ

-2x=-70+k.360.........kEZ

divide all terms by -2

x=35-k.180.......kEZ