What is the relationship between the sine and cosine of complementary angles? how do we know it is true?

The relationships are obtained according to the sin wave and the cosine wave.
sin 90 = 1 while cosine 90 =0.
You can refer the wave forms for further details.

1. isolate the variable, in this case, d. subtract 35.5 on both sides of the equation.2. 52 subtracted by 35.5 is 16.53. therefore your answer would be d= 16.5this is the basics of pre algebra, isolating variable through adding, subtracting, multiplying, and dividing, if you have any other questions to ask just comment!