Find Angle B in an Isosceles Trapezoid with 50° Angle

Below is an isosceles trapezoid

If ∢D=50° ∢D=50°

Determine the value of ∢B ∢B ?

AAABBBDDDCCC50°

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Step-by-step video solution

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00:00 Find angle B
00:03 According to the given, it's an isosceles trapezoid
00:09 In a trapezoid, angles on the same leg sum to 180
00:23 Let's substitute the value of D to find B
00:34 Let's isolate angle B
00:46 And this is the solution to the question

Step-by-step written solution

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1

Understand the problem

Below is an isosceles trapezoid

If ∢D=50° ∢D=50°

Determine the value of ∢B ∢B ?

AAABBBDDDCCC50°

2

Step-by-step solution

Let's recall that in an isosceles trapezoid, the sum of the two angles on each of the trapezoid's legs equals 180 degrees.

In other words:

A+C=180 A+C=180

B+D=180 B+D=180

Since angle D is known to us, we can calculate:

180−50=B 180-50=B

130=B 130=B

3

Final Answer

130°

Practice Quiz

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True OR False:

In all isosceles trapezoids the base Angles are equal.

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