Question

If triangle ABC is congruent to triangle DEF, m angle-A = 50°, and m angle-E = 30°, what is m angle-C?

Answer 1

C. 100°

Explanation:

If ΔABC ≅ ΔDEF then

• m∠A = m∠D = 50°
• m∠B = m∠E = 30°
• m∠C = m∠F

The sum of the interior angles of a triangle is 180°

Therefore, m∠A + m∠B + m∠C = 180°

⇒ 50° + 30° + m∠C = 180°

⇒ 80° + m∠C = 180°

⇒ m∠C = 180° - 80°

⇒ m∠C = 100°