Prove that angle in a semi-circle is right angle.

Using vector method, prove that the angel in a semi circle is a right angle.

Show that each angle of a rectangle is a right angle.

Prove that the angle in a segment smaller than a semi-cricle is greater than a right angle.

Prove that if one angle of a triangle is equal to the sum of the other two angles, the triangle is right angled.

True/false If one angle in a parallleogram is a right angled, then it is necessary a rectangle.

Show that the bisectors of the base angles of a triangle can never enclose a right angle.

Prove that the bisectors of the angles of a linear pair are at right angles.