Question

Find the measure of Angle B

A. 50°
B. 55°
C. 60°
D. 65°

Answer 1

Option B. 55° is the correct answer

Step-by-step explanation:

"The sum of interior angles of a triangle is always 180°"

Given

m∠A=(3x+1)°

m∠B=(2x-1)°

m∠C = 40°

We know that

m∠A+m∠B+m∠C=180°

Putting the values of angles

$(3x+1) +(2x-1) +40 = 180\\3x+1+2x-1+40 = 180\\5x+40=180$

Subtracting 40 from both sides

$5x+40-40=180-40\\5x=140$

Dividing both sides by 5

$\frac{5x}{5} = \frac{140}{5}\\x=28$

We have to find Angle B,

So

m∠B = 2x-1 = 2(28)-1 = 56-1 = 55°

Hence,

m∠B=55°

Option B. 55° is the correct answer

Keywords: Triangle, Interior angles

Learn more about triangles at:

• brainly.com/question/12896802
• brainly.com/question/12973601

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