किसी Δ ABC में यदि ∠A - ∠B = 40° तथा ∠B - ∠C = 10° हो तो ∠B = ? - - Kisi Δ ABC Me Yadi ∠A - ∠B = 40° Tatha ∠B - ∠C = 10° Ho To ∠B = ? Maths in hindi, triangles 60° question answers in hindi pdf 80° questions in hindi, Know About 70° Maths online test Maths notes in hindi quiz book 50°