Question

prove that the sum of angles of a triangle is 180 degree​

Answer 1

We draw a line parallel to AB that passes

through point C.

Angles C and C' are vertical angles,

therefore ∠C = ∠C'.

Angles B and B' are corresponding angles,

therefore ∠B = ∠B'.

Angles A and A' are corresponding angles, therefore ∠A = ∠A'.

So, the angle sum ∠A + ∠B + ∠C is equal to the angle sum ∠A' + ∠B' + ∠C'.

The three angles A', B', and C' form together a straight angle (they are along the line l).

So, their angle sum is 180°. But then the angle sum ∠A + ∠B + ∠C must also be 180

Answer 2

Answer:

x + x + x = 180

Step-by-step explanation:

3 x = 180

x = 180 ÷ 3 = 60

x = 60

if take as a polygon

n - 2 × 180 = 3 - 2 × 180

= 1 × 180 = 180