An equivalent expression is an expression that is equal. You need to find if the left and right side of the equal signs are equal to each other by reducing each to simplest terms.
Each of the expressions can be multiplied to find lowest terms by removing the parenthesis.
The side opposite the angle 19 degrees is given by 15sin 19 = 4.9 units, while the side adjacent the angle 19 degrees is given by 15cos 19 = 14.2 units.
