If the side opposite angle A of a right triangle is 30 meters and the hypotenuse is 90 meters what is the sin of angle a?

Remember Sin( angle) = opposite / hypotenuse.

Hence

Sin(A) = 30/90

Cancel down by '30'0

Sin(A) = 1/3 = 0.333333.....

A = Sin^(-1) 0.33333.....

A = 19.47122063..... degrees.

NB Careful with your triangle labelling.

Angles are always shown with a CAPITAL letter. 'A'.

The side opposite to the given angle is small/lower case of the same letter 'a'.

Similarly , ;B; & 'b; and 'C' & 'c'.