Question

all sums on quadrilateral with solutions

Answer 1

Sum of angles of a quadrilateral are discussed here.

We know, the sum of the angles of a triangle = 180°

Since there are two triangles,

therefore, the sum of two triangles is 180° + 180° = 360°






Note: The sum of the four angles is 360°.
1. In a quadrilateral ABCD, ∠A = 100°, ∠B = 105° and ∠C = 70°, find ∠D.

Solution: 

Here the sum of the four angles

or, ∠A + ∠B + ∠C + ∠D = 360°

We know, ∠A = 100°, ∠B = 105° and ∠C = 70°

or, 100° + 105° + 70° + ∠D = 360°

or, 275° + ∠D = 360°

∠D = 360° - 275° 

Therefore, ∠D = 85°