Question

6. The sides of a quadrilateral ABCD are produced in order. The ext. angleB = 70", ext. angelC = 100
and ext. angleD = 85. Find the measure of ext. angleA
[Hint: If the sides of a quadrilateral are produced in order. The sum of
the exterior angles so formed is equal to 4rtangleS]85
100%)
70​

Answer 1

∠C=180−aSum of all the angles of a quadrilateral is:∠A+∠B+∠C+∠D=360 o ⇒180−b+x+180−a+y=360⇒360−a−b+x+y=360

In quadrilateral ABCD, ∠A=180−band ∠C=180−aSum of all the angles of a quadrilateral is:∠A+∠B+∠C+∠D=360 o ⇒180−b+x+180−a+y=360⇒360−a−b+x+y=360⇒a+b=x+y