When a triangle is formed inside a semicircle, two lines from either side of the diameter meet at a point on the circumference at a right angle. The angle in a semicircle is a right angle of \(90 ...

The angle at the circumference in a semicircle is a right angle. Angle APB = 90° This is because the angle at the centre is 180° and the angle on the circumference is half the angle in the ...