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If the line `y = mx - (m-1)` cuts the circle `x^2+y^2=4` at two real and distinct points thenA. `m in (1, 2)`B. `m=1`C. `m=2`D. `m in R` |
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Answer» Correct Answer - D If the line `y= mx-(m-1)` cuts the circle in two distinct points, then Length of the perpendicular from the centre `lt` Radius. `rArr |(mxx0-0-(m-1))/(sqrt(m^(2)+1))| lt 2` `rArr (|m-1|)/(sqrt(m^(2)+1))lt2` `rArr (m-1)^(2)lt 2(m^(2)+1)` `rArr m^(2)+2m+1 gt 0` `rArr (m+1)^(2)gt0`, which is true for all `m in R`. Hence, option (d) is correct. `ul("ALITER")` The equation of the line is `y-1=m(-1)`. Clearly, it passes through (1, 1) which is an interior point of the circle. So, the line cuts the circle for all values of m. |
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