CBSE Class 12 Sample Paper for 2020 Boards

Class 12
Solutions of Sample Papers and Past Year Papers - for Class 12 Boards

## The magnitude of projection of  (2i − j + k ) on (i − 2j + 2k ) is _______

### Transcript

Question 15 (OR 1st Question) The magnitude of projection of (2๐ ฬ โ ๐ ฬ + ๐ ฬ) on (๐ ฬ โ 2๐ ฬ + 2๐ ฬ) is _______ Projection of vector ๐ โ on ๐ โ = ๐/|๐ โ | (๐ โ. ๐ โ) Let ๐ โ = 2๐ ฬ โ ๐ ฬ + ๐ ฬ ๐ โ = ๐ ฬ โ 2๐ ฬ + 2๐ ฬ (๐ โ . ๐ โ) = (2 ร 1) + (โ1 ร โ2) + (1 ร 2) = 2 + 2 + 2 = 6 Magnitude of ๐ โ = โ(12+(โ2)2+22) |๐ โ | = โ(1+4+4) |๐ โ | = โ9 |๐ โ | = 3 Projection of ๐ โ on ๐ โ = 1/|๐ โ | (๐ โ. ๐ โ) = 1/3 ร 6 = 2 โด Magnitude of projection is 2 units

#### Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.