Question

In triangle ABC A+1/2B+C=140 then find B

Answer 1

Step-by-step explanation:

since a+b+c =180°

so we can calculate this

Answer 2

∠B = 80°

Step-by-step explanation:

In triangle ABC ,

Using angle sum property of triangle :

∠A+∠B+∠C=180°

∠A+∠C=180-∠B ----1

We are given that ∠A+1/2∠B+∠C=140

$\frac{1}{2} \angleB = 140-(\angle A+\angle C)$

Using 1

$\frac{1}{2} \angleB = 140-(180-\angle B)\\\frac{1}{2} \angleB = 140-(180-\angle B)\\40=\angle B - \frac{1}{2} \angle B\\40=\frac{1}{2} \angle B\\80 = \angle B$

Hence ∠B = 80°

#Learn more:

In triangle abc angle a+b=65 and angle b+c=140 then find find angle b and c​

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