The equation of circle with centre (1, -2) and radius 4 cm is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e x2 + y2 – 2x + 4y = 11
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Understanding Tricks |
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Application Formula for center of circle ⇒ (x - a)2 + (y - b)2 = r2 So ⇒ (x - 1)2 + (y + 2)2 = 42 ⇒ x2 + 1 - 2x + y2 + 4 + 4y = 16 ⇒ x2 - 2x + y2 + 4y = 16 - 5 ⇒ x2 - 2x + y2 + 4y = 11 |
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Hence x2 + y2 – 2x + 4y = 11 |