NIMCET 2014 — Mathematics PYQ
NIMCET | Mathematics | 2014The condition that the line lx+my+n=0 becomes a tangent to the ellipse a2x2+b2y2=1, is:
Choose the correct answer:
- A.
a2l+b2m+n=0
- B.
al2+bm2=n2
a2l2+b2m2=n2
Explanation
Solution
Given equation of the line:
lx+my+n=0
Rewriting the line equation in slope-intercept form (y=mx+c):
my=−lx−n
y=(−ml)x−mn
Comparing this with y=Mx+C, we get:
M=−ml
C=−mn
For a line to be tangent to the ellipse a2x2+b2y2=1, the condition is:
C2=a2M2+b2
Substituting the values of M and C:
(−mn)2=a2(−ml)2+b2
m2n2=m2a2l2+b2
Multiplying the entire equation by m2:
n2=a2l2+b2m2
Correct Option: 4
Explanation
Solution
Given equation of the line:
lx+my+n=0
Rewriting the line equation in slope-intercept form (y=mx+c):
my=−lx−n
y=(−ml)x−mn
Comparing this with y=Mx+C, we get:
M=−ml
C=−mn
For a line to be tangent to the ellipse a2x2+b2y2=1, the condition is:
C2=a2M2+b2
Substituting the values of M and C:
(−mn)2=a2(−ml)2+b2
m2n2=m2a2l2+b2
Multiplying the entire equation by m2:
n2=a2l2+b2m2
Correct Option: 4
