Question

ADC is a straight line.

Answer 1

Applying the triangle sum theorem, the size of ∠BDC = 95°.

What is the Triangle Sum Theorem?

All three interior angles of any triangle have a sum that equals 180 degrees, based on the triangle sum theorem.

The diagram attached below shows the following:

• m∠BAD = 55°
• m∠BCD = 25°
• m∠ABD = 2x°
• m∠CBD = 3x°

Thus:

55 + 2x + 3x + 25 = 180 (triangle sum theorem).

• Add like terms

80 + 5x = 180

5x = 180 - 80

5x = 100

x = 20

Therefore,

m∠BDC = 180 - (3x + 25) (triangle sum theorem)

• Plug in the value of x

m∠BDC = 180 - (3(20) + 25)

m∠BDC = 95°

Therefore, applying the triangle sum theorem, the size of ∠BDC = 95°.

Learn more about triangle sum theorem on:

brainly.com/question/7696843