Question

sin45cos30- sin30cos45= sin x . what is the value of x?

Answer 1

This question is asking if you know the sin and cos of special angles

angle sin cos
0 sqrt(0)/2 sqrt(4)/2
30 sqrt(1)/2 sqrt(3)/2
45 sqrt(2)/2 sqrt(2)/2
60 sqrt(3)/2 sqrt(1)/2
90 sqrt(4)/2 sqrt(0)/2

the cosine goes in the opposite direction of the sine
You should memorize the actual numbers
angle sin cos
0 0 1
30 1/2 sqrt(3)/2
45 sqrt(2)/2 sqrt(2)/2
60 sqrt(3)/2 1/2
90 1 0