Question:medium

Let two non-collinear vectors $\hat{a}$ and $\hat{b}$ form an acute angle. A point P moves, so that at any time t the position vector $\overline{OP}$, where O is origin, is given by $\hat{a}\sin t+\hat{b}\cos t.$ when P is farthest from origin O, let M be the length of OP and $\hat{u}$ be the unit vector along $\overline{OP,}$ then

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Logic Tip: The sum of two vectors scaled identically (like multiplying both by $1/\sqrt{2}$) will point in the exact same direction as the unscaled sum. Hence, the unit vector of $k\vec{A}$ is simply the unit vector of $\vec{A}$ (for any $k>0$).
Updated On: Apr 28, 2026
  • $\hat{u}=\frac{\hat{a}+\hat{b{|\hat{a}+\hat{b}|}$ and $M=(1+\hat{a}\cdot\hat{b})^{\frac{1}{2$
  • $\hat{u}=\frac{\hat{a}-\hat{b{|\hat{a}-\hat{b}|}$ and $M=(1+\hat{a}\cdot\hat{b})^{\frac{1}{2$
  • $\hat{u}=\frac{\hat{a}+\hat{b{|\hat{a}+\hat{b}|}$ and $M=(1+2\hat{a}\cdot\hat{b})^{\frac{1}{2$
  • $\hat{u}=\frac{\hat{a}-\hat{b{|\hat{a}-\hat{b}|}$ and $M=(1-2\hat{a}\cdot\hat{b})^{\frac{1}{2$
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The Correct Option is A

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