Answers

2016-05-06T19:12:17+05:30
∠A+∠B+∠C= 180°
x+3x+y=180°
4x+y=180°
operating 3×4x+y-3y-5x=3×180-30°
12x+5x=540°-30°
17x=510°
x=30°
∠A=30
∴∠B=3x=3×30=90
HENCE IT IS A RIGHT ANGLE
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