Question

Which of these equations is always true?

Answer 1

Answer:
sin(x)=cos(90*-x)
Explanation:
Looking at the graphs of sin(x) and cos(x), you can see that the peaks of the graph are separated by a value of pi/2. If you convert that value into degrees, then the two graphs are separated by 90*. Another way of thinking is from the unit circle. sin(x) = 1 at 90*, and cos(x)=1 at 0*. The difference is still 90*.