Question

In figure 3.8, ∠ACD is an exterior angle of ΔABC. ∠B =40°,∠A=70°. Find the measure of ∠ACD.

Answer 1

Angle ACD= angle A+ angle B
40+70=110
Because exterior angle is equal to the sum of two interior angles.

Answer 2

Answer:

In figure 3.8, ∠ACD is an exterior angle of ΔABC. ∠B =40°,∠A=70°.

the measure of ∠ACD = 110°

Step-by-step explanation:

in a triangle sum of all angles = 180°

∠ABC  + ∠BAC +  ∠ACB = 180°

=> ∠B + ∠A +  ∠ACB = 180°

=> 40° + 70° + ∠ACB = 180°

=> ∠ACB = 70°

∠ACB + ∠ ACD = 180°  ( straight line)

=> 70° + ∠ ACD = 180°

=> ∠ ACD = 110°