Banner 0
Banner 1
Banner 2
Banner 3
Banner 4
Banner 5
Banner 6
Banner 7
Banner 8
Banner 9

Q.

The directions cosines of two lines are connected by relations l+m+n=0 and 4l is the harmonic mean between m and n then

see full answer

High-Paying Jobs That Even AI Can’t Replace — Through JEE/NEET

🎯 Hear from the experts why preparing for JEE/NEET today sets you up for future-proof, high-income careers tomorrow.
An Intiative by Sri Chaitanya

a

l1l2+m1m2+n1n2=32

b

l1l2+m1m2+n1n2=-32

c

l1l2+m1m2+n1n2=12

d

l1l2+m1m2+n1n2=-12

answer is B.

(Unlock A.I Detailed Solution for FREE)

Best Courses for You

JEE

JEE

NEET

NEET

Foundation JEE

Foundation JEE

Foundation NEET

Foundation NEET

CBSE

CBSE

Detailed Solution

l+m+n=04l=2mnm+n⇒2lm−mn+2ln=0by eliminating n, we get2lm2−lm−1=0⇒l1m1=1,l2m2=−12 and ⇒n1n2=−2∴l1l2+m1m2+n1n2=1−12−2=−32
Watch 3-min video & get full concept clarity

courses

No courses found

score_test_img

Get Expert Academic Guidance – Connect with a Counselor Today!

whats app icon
The directions cosines of two lines are connected by relations l+m+n=0 and 4l is the harmonic mean between m and n then