In: Math
Normals are drawn at point P,Q,R lying on parabola y2=4x which intersect at (3,0) then area of △PQR is?
We know that standard equation of parabola is given as-
y² = 4ax
On differeniating we get
2y dy/dx=4
Slope of tangent =2/y
Slope of normal=−y/2
Equation of normal
y=(−y/2)(x−3)
y= (-xy -3y)/2
2y = -xy -3y
2y = -y(x+3)
2=3−x
2-3 = -x
-1=-x
x=1
x=1
y=0
Given that
Points P, Q, R are (0,0),(1,2) & (1,−2)
Base QR=4
Height =1
We know that
area of triangle =1/2 base x height
Thereforewe have,
Area =1/2 X 4 X1
=2.
Hence area of the traingle = 2.
Area of triangle = 2.