Question 27
Coordinate GeometryThe equation of a circle is x2 + y2 − 8x + 9y + 15 = 0. Find its radius.
- A.√5
- B.½√15
- C.½√85
- D.√85
Show the answer and explanation
Answer: C (½√85)
Explanation
Centre (4, −9/2); r² = 16 + 81/4 − 15 = 85/4, so r = ½√85.
The equation of a circle is x2 + y2 − 8x + 9y + 15 = 0. Find its radius.
Answer: C (½√85)
Centre (4, −9/2); r² = 16 + 81/4 − 15 = 85/4, so r = ½√85.