Answer:
Given :
Or we can say that A ray ST is perpendicular to Ray SR.
By the definition of Perpendicular lines: A perpendicular lines are lines that intersect at a right angle.
⇒ is right angle.
Then, by the definition of the right angle states that the angle bounded by the two perpendicular lines i.e, an angle of .
⇒
Addition Angle theorems states that the sum of measure of two angle of an interior angle.
then, by the definition of the addition angle theorem we have ;
......[1]
Now, by substituting the value of in above equation[1];
......[2]
Subtraction property of Equality states that subtract the same number from both sides of an equation.
Now, subtract from both sides of an equation [2];
On simplify we get,
Hence proved!
The figure as you can see in the attachment.