If the coordinates of the points A,B,C be (-1,3,2),(2,3,5) and (3,5,-2) respectively, then angle A=

Answers (1)
N neha

As we discussed in concept

Ange between two lines in terms of direction cosines and direction ratios -

If two lines having direction ratios a1,b1,c1 and a2,b2,c2 then the angle between them is given by

\cos \Theta = \frac{a_{1}a_{2}+b_{1}b_{2}+c_{1}c_{2}}{\sqrt{a{_{1}}^{2}+b{_{1}}^{2}+c{_{1}}^{2}}\sqrt{a{_{2}}^{2}+b{_{2}}^{2}+c{_{2}}^{2}}}

If two lines have direction ratios as l1,m1,n1 and l2,m2,n2 then the angle betwee them is given by

\cos \Theta = l_{1}l_{2}+m_{1}m_{2}+n_{1}n_{2}

 Direction ratio of AB = (3,0,3)

Direction ratio of AC = (4,2,-4)

So, Cos A = \frac{3\times 4+0\times 2\:+3\times -4}{\sqrt{9+0+9}\times \sqrt{16+4+16}}

                = 0

A\:=\:90^{\circ}

Preparation Products

JEE Main Rank Booster 2021

This course will help student to be better prepared and study in the right direction for JEE Main..

₹ 13999/- ₹ 9999/-
Buy Now
Knockout JEE Main April 2021 (Subscription)

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 4999/-
Buy Now
Knockout JEE Main April 2021

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 22999/- ₹ 14999/-
Buy Now
Knockout JEE Main April 2022

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 34999/- ₹ 24999/-
Buy Now
Knockout BITSAT 2021

It is an exhaustive preparation module made exclusively for cracking BITSAT..

₹ 4999/- ₹ 2999/-
Buy Now
Exams
Articles
Questions