Question

Examine the figure below.

Answer 1

*see attachment for diagram

Answer:

✔️m<BAC = 72°

✔️m<BCD = 108°

Step-by-step explanation:

Given:

m<ABC = (4x - 16)°

m<ACB = (5x + 7)°

Find the numerical value of m<ABC, m<ACB, m<BAC, and m<BCD.

First we need to determine the value of x.

The ∆ given is an isosceles triangle with two equal sides, therefore, the angles opposite the two equal sides would also be equal.

Therefore:

(4x - 16)° + 2(5x + 7)° = 180° (sum of ∆)

Solve for x

4x - 16 + 10x + 14 = 180

Add like terms

14x - 2 = 180

Add 2 to both sides

14x = 182

Divide both sides by 14

x = 13

Find the measure of each angle by plugging in the value of x where necessary:

✔️m<ABC = (4x - 16)° = 4(13) - 16

m<ABC = 36°

✔️m<ACB = (5x + 7)° = 5(13) + 7

m<ACB = 72°

✔️m<BAC = m<ACB (both are base angles of the isosceles ∆, so they are equal)

Therefore,

m<BAC = 72°

✔️m<BCD = m<ABC + m<ACB (exterior angle theorem of a triangle)

m<BCD = 36 + 72 (Substitution)

m<BCD = 108°

Therefore, the angle measures that are correct are:

✔️m<BAC = 72°

✔️m<BCD = 108°