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KCET · Maths · Application of Derivatives

The point on the curve \(y^{2}=x\), the tangent at which makes an angle \(45^{\circ}\) with \(X\)-axis is

  1. A \(\left(\frac{1}{4}, \frac{1}{2}\right)\)
  2. B \(\left(\frac{1}{2}, \frac{1}{4}\right)\)
  3. C \(\left(\frac{1}{2}, \frac{-1}{2}\right)\)
  4. D \(\left(\frac{1}{2}, \frac{1}{2}\right)\)
Verified Solution

Answer & Solution

Correct Answer

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

Step-by-step Solution

Detailed explanation

Given,
\[
y^{2}=x
\]
\[
\begin{aligned}
&\Rightarrow \quad 2 y \frac{d y}{d x}=1 \\
&\Rightarrow \quad \frac{d y}{d x}=\frac{1}{2 y}=\text { Slope }
\end{aligned}
\]
Also given, \(\quad \theta=45^{\circ}\)
\(\therefore\) Slope \(\tan 45^{\circ}=1 \Rightarrow \frac{1}{2 y}+1\)
\(\Rightarrow \quad y=\frac{1}{2}\)
From Eq. (i), if \(y=\frac{1}{2}\), then \(x=\frac{1}{4}\)
\(\therefore\) Required point is \(\left(\frac{1}{4}, \frac{1}{2}\right)\).