In a right triangle sin (2x°)=cos (3x-10)°. What is the value of x?

1 answer

by the complimentary property:
cos (3x-10)°
= sin(90 - (3x-10) )
= sin (100 - 3x)

so sin(2x) = sin(100-3x)
2x = 100-3x
5x = 100
x = 20

check:
sin (2x) = sin 40°
cos(3x-10) = cos 50°

indeed sin 40 = cos 50