Question
The slope m of a tangent through the point (7, 1) to the circle x2+y2=25 satisfies the equation
Answer: Option C
:
C
Equation of a tangent to x2+y2 = 25 is y = mx ± 5√1+m2
This passes through (7, 1) ⇒ 1 = 7m ± 5√1+m2
⇒(1−7m)2=25(1+m2) ⇒49m2−14m+1=25+25m2 ⇒24m2−14m−14=0
⇒12m2 - 7m - 12 = 0
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:
C
Equation of a tangent to x2+y2 = 25 is y = mx ± 5√1+m2
This passes through (7, 1) ⇒ 1 = 7m ± 5√1+m2
⇒(1−7m)2=25(1+m2) ⇒49m2−14m+1=25+25m2 ⇒24m2−14m−14=0
⇒12m2 - 7m - 12 = 0
Was this answer helpful ?
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