Question

21. Prove that the sum of all the angle of a quadrilateral is 360°?​

Answer 1

Answer:

U could prove it by saying that dividing it into two triangle using a diagonal... Then U could say that the sum of angles of one triangle is 180* and as there are two triangle in the quadrilateral its 360*

Hope it gives you the basic idea of how to prove it...

You have to start practicing how to develop a idea instead of relying totally on solutions...

Hope it helps you to get good marks:)..

Mark as brainliest plzz...

Answer 2

$\huge\sf \orange{hello}...$

Statement :

sum of the angles of quadrilateral is 360°

To Prove :

∠A + ∠B + ∠C + ∠D = 360°

Proof :

In ∆ ABC , m∠4 + m∠5+m∠6 = 180°

[ using angle a property of a triangle]

Also , in ∆ ADC , m∠1 + m∠2+m∠3= 180°

Sum of the measures of ∠A, ∠B , ∠C and ∠D of a quadrilateral

m∠4 + m∠5+ m∠6 + m∠1 + m∠2 +m∠3 = 180°+ 180°

→ ∠A + ∠B + ∠C + ∠D = 360°

Thus , sum of measure of four angles of quadrilateral is 360°.