Question

Δ ABC is isosceles. Angles B and C are congruent. The m∠A = 40°, m∠B = (3x + 1)°. Find x.

A) 13
B) 23
C) 46.3
D) 70

Answer 1

The other person is correct, x = 23

Answer 2

Answer: Option 'B' is correct.

Explanation:

Since we have given that

ΔABC is an isosceles and ∠B and ∠C are congruent.

So, ∠B=∠C=3x+1

∠A=
`40\textdegree`

As we know the formula for "Sum of three angles in a triangle ":

`\angle A+\angle B+\angle C=180\textdegree\\\\40\texdegree+3x+1+3x+1=180\textdegree\\\\42\textdegree+6x=180\textdegree\\\\6x=180\textdegree-42\textdegree\\\\6x=138\textdegree\\\\x=(138)/(6)\\\\x=23\textdegree`

Hence, Option 'B' is correct.