Find a point on the curve $y = (x-2)^2$ at which the tangent is parallel to the chord joining the points (2, 0) and (4, 4). |
$(3,1)$ $(2,0)$ $(4,4)$ $(1,1)$ |
$(3,1)$ |
The correct answer is Option (1) → $(3,1)$ Slope of chord joining points (2, 0) and (4, 4) = $\frac{4-0}{4-2}= 2$. Let $P(x_1,y_1)$ be a point on the given curve at which the tangent is parallel to the chord joining the points (2, 0) and (4, 4). The given curve is $y = (x-2)^2$ ...(i) Differentiating (i) w.r.t. x, we get $\frac{dy}{dx} = 2(x-2)$. ∴ Slope of tangent at $P(x_1, y_1) =\left(\frac{dy}{dx}\right)_P=2(x_1-2)$. Since the tangent to the given curve at $P(x_1,y_1)$ is parallel to the chord, slope of tangent at P = slope of chord $⇒2(x_1-2)=2⇒ x_1-2=1⇒x_1=3$. As $P(x_1,y_1)$ lies on the curve (i), $y_1 = (x_1-2)^2$ $⇒ y_1 = (3-2)^2 ⇒y_1 = 1$. Hence, the required point is (3, 1). |