11Q 83
a) straight line
Q102) |Z1| = 1 and |Z2 - 3 - 3i| = 1 , then minimum value of |Z1 - Z2| = ? a) 3√2 b) 3√2 – 1 c) 3√2 - 2 d) None of these. i'm getting answer (a) ,but is given (c).
Q83) What is the locus of centre of a circle that touches two other circles externally ?
a) straightline b) parabola c) Hyperbola d) None of these.
confused between parabola or hyperbola
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10 Answers
1357for first minimum distance = distance between the centres of circles-r1-r2=3√3 -1 -1=3√3 -2
11102)
|Z1| = 1
|Z2 - 3 - 3i| = 1
therefore
|Z1| = |Z2 - 3 - 3i|
Z1 - Z2 = -3 - 3i
|Z1 - Z2| = √9 + 9
|Z1 - Z2| = 3√2
Option a)
1357It is hyperbola
just from the property that the difference of distance of a point from two points is constant
1Take 2 circles of equal radii a distance apart ... then draw a series of circle touching both the circles externally ... the centre of these circles will appear to be moving in a st. line !