In Fig. 6.9, BC = CA and ∠A = 40°. Then, ∠ACD is equal to
a. 40°
b. 80°
c. 120°
d. 60°

Solution:

Given, BC = CA

Also, ∠A = 40°

We have to find the value of ∠ACD.

We know that the angles opposite to the equal sides are equal.

So, ∠A = ∠B = 40°

The exterior angle theorem states that the measure of an exterior angle is equal to the sum of the measures of the two opposite interior angles of the triangle.

By exterior angle property,

∠ACD = ∠A + ∠B

= 40° + 40°

= 80°

Therefore, ∠ACD = 80°

✦ Try This:In △PQR, if ∠Q = 90° and ∠R = 35°, find ∠P (in degrees)

☛ Also Check: NCERT Solutions for Class 7 Maths Chapter 6

NCERT Exemplar Class 7 Maths Chapter 6 Problem 19

In Fig. 6.9, BC = CA and ∠A = 40°. Then, ∠ACD is equal to: a. 40°, b. 80°, c. 120°, d. 60°

Summary:

In Fig. 6.9, BC = CA and ∠A = 40°. Then, ∠ACD is equal to 80°

☛ Related Questions:

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• Which of the following statements is not correct? a. The sum of any two sides of a triangle is great . . . .
• In ∆PQR, if PQ = QR and ∠Q = 100°, then ∠R is equal to: a. 40°, b. 80°, c. 120°, d. 50°