Question

15. In the figure below, line land m are parallel. What is the
cand mare parallel. What is the value of /_a + /_b in the given
figure?
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Answer 1

Given that,

l || m

so,

angle B = 90°

( being Alternate interior angle to the 90° angle of ∆)

Also,

angle A = angle B

( being vertically opposite angle)

so,

angle A = 90°

we have to find angle A+ angle B

so,

Angle A + Angle B = 90° + 90°

Angle A + Angle B = 180°

So the sum of angle A and B is 180° .