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Provide solution for RD Sharma Maths Class 12 Chapter 26 Directions Cosines and Direction Ratios Exercise Multiple Choice Question, question 16.

Answers (1)

Final Answer:

(d) \sqrt{\alpha^2+\gamma ^2}

Hint: Use distance formula

Given:

Point P (\alpha ,\beta ,\gamma )

To Find: Distance of P from y-axis

Solution: The distance of the point

(\alpha ,\beta ,\gamma )  from y-axis whose coordinates are

(0 ,\beta ,0 )

Distance formula is

\begin{aligned} &d=\sqrt{\left(x_{2}-x_{1}\right)^{2}+\left(y_{2}-y_{1}\right)^{2}+\left(z_{2}-z_{1}\right)^{2}} \\ &=\sqrt{(0-\alpha)^{2}+(\beta-\beta)^{2}+(0-\gamma)^{2}} \end{aligned}

where

\begin{aligned} &\left(x_{1}, y_{1}, z_{1}\right)=(\alpha, \beta, \gamma) \&\left(x_{2}, y_{2}, z_{2}\right)=(0, \beta, 0) \\ &d=\sqrt{\alpha^{2}+\gamma^{2}} \end{aligned}

Therefore, option(d) is correct.

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infoexpert24

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