Question

Prove that if one angle of a triangle is equal to the
sum of the other two angles, the triangle is right angled.
​

Answer 1

Answer:

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 + angleC) =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.

So, it is right angled triangle

Thank you………..

Answer 2

Answer:

Sol: Given - B = A+C ------(1)

In ABC ,By Angle Sum Property of Triangle,

A +B+C = 180°

B + (A+C) = 180°

B + B = 180° [From equation (1)]

2B = 180°

B = 180°/2 = 90°

Now ,here B =90° it means ABC is a right angled triangle