Question

In fig 9.22, two angles have been indicated. Find ∆ ACD​

Answer 1

Answer:

180 - ( 60 + 55 ) = 180 - 115 = 65

so the answer is ∆ ACD = 65

Answer 2

☆ In △ ABC.

• ∠BAC = 60°.

• ∠ABC = 55°.

• ∠ACB = ?.

☆ The Sum of all the interior angles of a triangle is always equal to 180°.

☆ By using angle sum property.

= ∠BAC + ∠ABC + ∠ACB = 180°.

= 60° + 55° + ∠ACB = 180°.

= 115° + ∠ACB = 180°.

= ∠ACB = 180° - 115°.

= ∠ACB = 65°.

☆ The sum of an exterior angle and interior angle is always equal to 180°.

= ∠ACB + ∠ACD = 180°.

= 65° + ∠ACD = 180°.

= ∠ACD = 180° - 65°.

= ∠ACD = 115°.

☆ Hence, the measure of ∠ACD is 115°.