Q. 2 E

Sum of the three exterior angles of a triangle is __________
A. two right angles

B. three right angles

C. one right angle

D. four right angles

Answer :

We know that an exterior angle of a triangle is equal to the sum of the interior opposite angles.


⇒ ∠A + B = external C


A + C = external B


C + B = external A


Adding above three, we get


2A + 2 B + 2C = sum of the three external angles


2(A + B + C) = sum of the three external angles


We know that the sum of the angles of a triangle is 180°.


2× 180° = sum of the three external angles


Sum of the three external angles = 4 × 90°

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