Foundation
Mathematics Foundation
Tangent to Circle
Question

In the figure given below ∠AOB = 80º, arc AC = arc BC, then ∠CAB is equal to

90º    

60º    

70º    

80º    

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Solution

We have, 
∠ACB = 12 ∠AOB
∠ACB = 12 (80º)         
        = 40º
    Now in triangle ABC 
∴  AC = BC
∴  ∠CAB = ∠CBA        --------(1)
    and ÐACB + ∠CBA + ∠CAB = 180
    ∠CBA + ∠CAB = 180º – 40º    
    ∠CBA + ∠CAB = 140º        --------(2)
    from equation (1) and (2)
    2 ∠CAB = 140º
   ∠CAB = 70º