Question

In the given figure, CD is a direct common tangent to two circles intersecting each other at A and B. Then, ∠CAD + ∠CBD equals

(a) 120° 

(b) 90° 

(c) 360° 

(d) 180°

Answer 1

∴ ∠CAD = ∠CAB + ∠DAB = ∠BCD + ∠BDC 

Now, ∠CAD + ∠CBD = ∠BCD + ∠BDC + ∠CBD = 180° (Angle sum property in ∆ BDC)