Question
Question: The number of real tangents that can be drawn on the ellipse 3x<sup>2</sup> + 5y<sup>2</sup> = 32 an...
The number of real tangents that can be drawn on the ellipse 3x2 + 5y2 = 32 and 25x2 + 9y2 = 450 passing through (3, 5) is:
A
0
B
2
C
3
D
4
Answer
3
Explanation
Solution
Since 3 x 32 + 5 x 52 - 32 > 0, the point (3, 5) lies outside the ellipse 3x2 + 5y2 = 32.
Also, 25 x 32 + 0 x 52 - 450 = 0, ∴ the point (3, 5) lies on the ellipse 25x2 + 9y2 = 450. So the required number of tangents is 3.