You are asked to find
[tex]\sin (\theta)=\sin (\theta-90^{\circ})[/tex]
The sin of an angle equals the opposite side divided by the hypotenuse, so the next drawing will help to find the answer:
[tex]\sin (\theta)=\frac{7}{\sqrt[]{6^2+7^2}}=\frac{7}{\sqrt[\square]{85}}[/tex]
The hypotenuse is the square root of 6 to the square plus 7 to the square because of the Pythagorean theorem. In order to have a rational denominator:
[tex]\frac{7}{\sqrt[]{85}}=\frac{7\cdot\sqrt[\square]{85}}{85}=\frac{7\cdot\sqrt[]{17}\cdot\sqrt[\square]{5}}{17\cdot5}[/tex]
Because
