Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • School
  • Need Solution for R.D.Sharma Maths Class 12 Chapter 23 Scalar or Dot Products Exercise 23.1 Question 20 Maths Textbook Solution.

Need Solution for R.D.Sharma Maths Class 12 Chapter 23 Scalar or Dot  Products  Exercise 23.1 Question 20 Maths Textbook Solution.

Answers (1)

Answer: \lambda =8

Hint: You must know the rules of solving vector.

Given:

\begin{aligned} &\vec{a}=2 \hat{\imath}+2 \hat{\jmath}+3 \hat{k} \\ &\vec{b}=-\hat{\imath}+2 \hat{\jmath}+\hat{k} \\ &\vec{c}=3 \hat{\imath}+\hat{\jmath} \end{aligned}

\vec{a}+\lambda \vec{b} \text{ is perpendicular to }\vec{c} \ then \ find \: \lambda

Solution: We have,

\begin{aligned} &\vec{a}=2 \hat{\imath}+2 \hat{\jmath}+3 \hat{k}, \quad \vec{b}=-\hat{\imath}+2 \hat{\jmath}+\hat{k}, \quad \vec{c}=3 \hat{\imath}+\hat{\jmath} \\ &\therefore \vec{a}+\lambda \vec{b}=2 \hat{\imath}+2 \hat{\jmath}+3 \hat{k}+\lambda(-\hat{\imath}+2 \hat{\jmath}+\hat{k}) \\ &\vec{a}+\lambda \vec{b}=(2-\lambda) \hat{\imath}+(2+2 \lambda) \hat{\jmath}+(3+\lambda) \hat{k} \end{aligned}

Given \: \: that \: \: \vec{a}+\lambda \vec{b} \: \: is \perp to \ \vec{c}

\therefore(\vec{a}+\lambda \vec{b}) \cdot \vec{c}=0 \\

\Rightarrow[(2-\lambda) \hat{\imath}+(2+2 \lambda) \hat{\jmath}+(3+\lambda) \hat{k}] \cdot(3 \hat{\imath}+\hat{\jmath}) \\

\Rightarrow 3(2-\lambda)+1(2+2 \lambda)=0 \\

\Rightarrow 6-3 \lambda+2+2 \lambda=0 \\

\lambda=8

Posted by

infoexpert21

View full answer

Crack CUET with india's "Best Teachers"

  • HD Video Lectures
  • Unlimited Mock Tests
  • Faculty Support
cuet_ads

Similar Questions

Latest Question