Q.

In the given figure, AT is tangent to a circle centred at O. If ∠CAT=40°, then ∠CBA is equal to

1 70°  
2 50°  
3 65°  
4 40°  

Ans.

(4)

Given, ∠CAT=40°

∠BAT=90°

⇒∠BAC+∠CAT=90°

⇒∠BAC=50°

⇒∠ACB=90°  [Angle in semi-circle]

In ∆ABC, ∠A+∠B+∠C=180°

⇒50°+∠B+90°=180°

⇒∠B=180°-140°=40°