Question

In the given figure, BC = CA and ∠A = 40°. Then, find ∠ACD

Answer 1

Answer:

Step-by-step explanation:

As we all know that the sum of all angles in a triangle is equal to 180°.

so,

angle BAC + Angle ABC + Angle ACB = 180°

40° + 70° + ACB = 180°

110° + ACB = 180°

Angle ACB = 180° - 110°

Angle ACB = 70°

Now we need to find Angle ACD.

As we know that the angle of a straight line is equal to 180°.

so,

Angle ACB + Angle ACD = 180°

70° + ACD = 180°

ACD = 180° - 70°

ACD = 110°

Refer the pic

Hope it helps

:)

Answer 2

Step-by-step explanation:

angle bac=angle abc(iscoceles triangle)

angle abc=40⁰

angle(abc+bac+acb)=180⁰(linear pair)

40⁰+40⁰+acb=180⁰

80⁰+acb=180⁰

acb=180⁰-80⁰

acb=100⁰

acb+acd=180⁰(linear pair)

100⁰+acd=180⁰

acd=180⁰-100⁰

acd=80⁰

2nd method

bac+cba=acd(exterior angle = sum of opposite angles)

40⁰+40⁰=acd

acd=80⁰

Hope it helps

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