Question

in a triangle angle A + B + angle C is equal to 180 degree prove that

Answer 1

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Answer 2

Let ABC be any triangle

In which measure of angleB is equal to the measure of remaining angles that is angleA and angleC

So, in triangle ABC,

angleA + angleC= angleB …………(1)

Now, in triangle

angle A +angle B+ angle C =180°

= angle B + ( angleA + angleB) =180°

= angleB + angleB =180°…………..from(1)

=2 angleB = 180°

= angle B = 180°/2

=angleB= 90°

So, one angle of triangleABC is 90° or if one angle of triangle is 90° this triangle is known as right angled triangle.