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Mathematics
Mathematics
Problem
The chord of contact of tangents from a point
P
P
P
to a circle passes through
Q
Q
Q
. If
l
1
l_1
l
1
and
l
2
l_2
l
2
are the lengths of tangents from
P
P
P
and
Q
Q
Q
to the circle, then
P
Q
PQ
P
Q
is equal to a.
l
1
+
l
2
2
\frac{l_1 + l_2}{2}
2
l
1
+
l
2
b.
l
1
−
l
2
2
\frac{l_1 - l_2}{2}
2
l
1
−
l
2
c.
l
1
2
+
l
2
2
\sqrt{l_1^2 + l_2^2}
l
1
2
+
l
2
2
d.
l
1
2
−
l
2
2
\sqrt{l_1^2 - l_2^2}
l
1
2
−
l
2
2
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