Question
Mathematics Question on Application of derivatives
The length of the subtangent to the curv x2y2=a4 at (−a,a) is
A
3a
B
2a
C
a
D
4a
Answer
2a
Explanation
Solution
We have, x2y2=a4⇒y2=x2a4
Differentiating w.r.t. x, we get
2ydxdy=x3−2a4
[dxdy](−a,a)=2(−a)3.a−2a4=1
Length of subtangent =dydxy=1a=a