C is a point outside circle with centre A. and radius r.

CB and CD are tangents segments whose length is t.

find area of triangle BCD in terms of r and t

Dear ajinka

CA = √r²+t²

sinθ =r/√r²+t²

cosθ = t/√r²+t²

AP =rsinθ  = r²/√r²+t²

BP =rcosθ = tr/√r²+t²

ΔBCD = =2ΔBCP = 2[ΔABC -ΔABP]

                        =2[rt/2   - 1/2 AB * BP]

                        =rt - {r²/√r²+t²}{ tr/√r²+t²}

                        =rt - r³t/(r²+t²)

                        =rt³/(r²+t²)

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