Question

If sin (x+20degrees)=cos x, find the value of x in degrees?

Answer 1

the value of sin and cos add up to 90

Answer 2

we know sin 45 = cos 45

Answer 3

so....sin(.x+20)+cosx=90?

Answer 4

x+20 = 45
x = 25

Answer 5

what? x=25?? how?

Answer 6

well, just remember one of trigonometry identity is sin(90-x) = cosx
so, convert cosx to sin(90-x)
sin (x+20)=cos x
sin (x+20)=sin(90 - x)
so, x+ 20 = 90 - x
2x = 70
x = 35 degrees