all angles are kept. It follows that ∠APD = ∠BPC = 90°. Preview. Now there are three triangles ABC, ACD and ABD. the sum of the three angles of a triangle = 180°. The angles of a triangle add up to 180 o, so an external angle equals the sum of the other two internal angles. The Circle Theorem that the Angle in a Semicircle is a Right Angle. Answer: Half of the circle. Transcript. Some of the other directions of the compass are Sikhism, Gnosticism, Judaism, Hinduism, Christianity, Atheism, Psychology, Philosophy, Jainism, Zoroastrianism, Buddhism, Taoism, Baha'i Faith, Babism, Rastafarianism, etc. lines will produce harmony. The sum of angles of a regular hexagon, equal to 720°, is calculated from the formula of the sum of the angles of a polygon as follows: S = (n - 2) 180° Where, S = Sum of angles of the hexagon n = 6 (number of sides of the hexagon) Therefore, S = (6 - 2) 180°    = 4 × 180°    = 720° Each angle is calculated by dividing the sum by number of sides as follows: Angle = S/n             = 720°/6             = 120° In Chinese Cosmology, each equilateral triangle is called a trigram. diameter is the chord if the other two sides of the right triangle are That is (180-2p)+ (180-2q)= 180. 120 +