Find Angle B in Quadrilateral ABCD: Using 140° and 80° Measurements

ABCD is a quadrilateral.

According to the data, calculate the size of ∢B ∢B .

AAABBBDDDCCC80140

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find angle B
00:09 The sum of angles in a quadrilateral is always equal to 360
00:15 Substitute appropriate values according to the given data
00:35 Collect terms and isolate D
00:55 And this is the solution to the question

Step-by-step written solution

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1

Understand the problem

ABCD is a quadrilateral.

According to the data, calculate the size of ∢B ∢B .

AAABBBDDDCCC80140

2

Step-by-step solution

As we know, the sum of the angles in a square is equal to 360 degrees, therefore:

360=A+B+C+D 360=A+B+C+D

We replace the data we have in the previous formula:

360=140+B+80+90 360=140+B+80+90

360=310+B 360=310+B

Rearrange the sides and use the appropriate sign:

360−310=B 360-310=B

50=B 50=B

3

Final Answer

50

Practice Quiz

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Indicates which angle is greater

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