Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Applications of Derivatives

Question:

The point on the curve $y^2=x$ where tangent makes 45° angle with x-axis is:

Options:

$\left(\frac{1}{2}, \frac{1}{4}\right)$

$\left(\frac{1}{4}, \frac{1}{2}\right)$

$(4,2)$

$(1,1)$

Correct Answer:

$\left(\frac{1}{4}, \frac{1}{2}\right)$

Explanation:

The correct answer is Option (2) - $\left(\frac{1}{4}, \frac{1}{2}\right)$

$y^2=x$  ...(I)

so differentiating wrt x

$2y\frac{dy}{dx}=1⇒\frac{dy}{dx}=\frac{1}{2y}$

when tangent makes 45° with x axis

$⇒\frac{dy}{dx}=\tan 45°=1$

$⇒\frac{1}{2y}=1$ so $y=\frac{1}{2}$

from (1) → $x=\frac{1}{4}$

point → $\left(\frac{1}{4}, \frac{1}{2}\right)$