Solve the question sin (x - 20) = cos (42) for x, where 0, x, 90.

62

22

28

68

You need to use the identity

cos (90-u) = sin (u)

if u=x-20

cos (90-x+20) = sin (x-20)

cos (110-x) = sin (x-20)

substituting in the original function

cos (110-x) = cos (42)

for the functions to be equal there input must be equal

110-x=42

x=68