CircleHard
Question
3 circle of radii 1, 2 and 3 and centres at A, B and C respectively, touch each other. An other circle whose centre is P touches all these 3 circles externally and has radius r. Also ∠PAB = θ & ∠PAC = α -
Options
A.cosθ = 
B.cos α = 
C.r = 
D.r = 
Solution
ᐃABC is right angle
Applying cosine rule in ᐃPAB
cos θ =
=
Again applying cosine rule in ᐃPAC
cos α =
∵ α + θ = 90o
α = 90o - θ cos α = sin θ
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