Question

Quadrilateral ABCD​ is inscribed in this circle.

What is the measure of angle B?

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Answer 1

132°

Explanation:

We use the circle theorem which states that :

Opposite angles in a cyclic quadrilateral add up to 180 .

Now we know that angles ADC and ABC add up to 180. So :

We make an equation and solve for x :

x+(3x-12) = 180

4x-12 = 180

4x = 192

x = 48

Now we substitute the value of x into Angle B :

3(48) -12 =

144 - 12 = 132

Angle B = 132 °

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