The area of the triangle formed by the tangents from the point (4, 3)t...
From P(4, 3) two tangents PT and PT′ are drawn to the circle x2+y2=9 with O(0, 0) as centre and r=3. To find the area of ΔPTT′ .
Let R be the point of intersection of OP and TT′,
Then, we can prove by simple geometry that OP is perpendicular bisector of TT′.
The equation of chord of contact from a point (x1, y1) to a circle x2+y2=r2 is xx1+yy1=r2
Hence, the equation of chord of contact TT′ from the point (4, 3) to the circle x2+y2=9 is 4x+3y=9
The length of perpendicular from a point (x1, y1) on a line
Now, OR= length of the perpendicular from O to TT′ is
Now, radius of circle OT=3
In triangle OTR, by Pythagoras theorem, we have
The distance between the points (x
1, y
1) and (x
2, y
2) is
∴ Area of the triangle PTT′ will be twice area of ΔPRT