Mathematics
In the given figure, QAP is the tangent at point A and PBD is a straight line.
If ∠ACB = 36° and ∠APB = 42°, find :
(i) ∠BAP
(ii) ∠ABD
(iii) ∠QAD
(iv) ∠BCD
Answer
(i) We know that,
The angle between a tangent and a chord through the point of contact is equal to an angle in the alternate segment.
∴ ∠BAP = ∠ACB = 36°.
Hence, ∠BAP = 36°.
(ii) We know that,
An exterior angle in a triangle is equal to the sum of two opposite interior angles.
In △APB,
∠ABD = ∠APB + ∠BAP = 42° + 36° = 78°.
Hence, ∠ABD = 78°.
(iii) From figure,
∠ADB = ∠ACB = 36° (Angles in same segment are equal)
In △PAD,
∠QAD = ∠APB + ∠ADB = 42° + 36° = 78°. [Exterior angle is equal to sum of two opposite interior angles.]
Hence, ∠QAD = 78°.
(iv) We know that,
The angle between a tangent and a chord through the point of contact is equal to an angle in the alternate segment.
∴ ∠ACD = ∠QAD = 78°.
From figure,
∠BCD = ∠ACB + ∠ACD = 36° + 78° = 114°.
Hence, ∠BCD = 114°.
Related Questions
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