If the angles of a quadrilateral are in A.P. whose common difference is 10∘, then find the angles of the quadrilateral.
Suppose that ∠A = x, then ∠B = x + 10∘,
∠C = x + 20∘ and ∠D = x + 30∘
So, we know that ∠A + ∠B + ∠C + ∠D = 2π
Putting these values , we get
(x) + ( x+10∘) + ( x+20∘) + ( x+30∘) = 360∘
⇒x= 75∘
Hence, the angles of the quadrilateral are 75∘, 85∘, 95∘, 105∘.