Equal angles at the
centre of the circle
stand on equal arc.
Don't need to prove
IMPORTANT TO REMEMBER
Theorem- The angle at
the centre of a circle is
twice the angle at the
circumference subtended
by the same arc.
Don't need to prove
IMPORTANT TO REMEMBER
Theorem- The angle in a
semicircle is a right angle.
IMPORTANT TO REMEMBER
Need to prove
Need to prove
IMPORTANT TO REMEMBER
shorter as, Angles
in the same
segment are equal.
Chords
Need to
prove
Theorem- The
perpendicular
bisector of a chord
passes through
the centre of the
circle.
need to
prove
Theorem 1- The
perpendicular from the
centre of a circle to a
chord bisects the chord.
Theorem 2- The line from
the centre of a circle to
the midpoint of a chord is
perpendicular to the chord.
Need to prove
Need to
prove
Theorem- Chords that are
equidistant from the centre of
the circle are equal.
with this question i saw the conce
Cyclic Quadrilaterals
Theorem- The
opposite angles
of a cyclic
quadrilateral are
supplementary.
Need to prove
IMPORTANT TO REMEMBER
Theorem- An
exterior angle of a
cyclic quadrilateral is
equal to the interior
opposite angle.
Need to
prove
Theorem- If the opposite
angles in a quadrilateral are
supplementary then the
quadrilateral is cyclic.
This is also a test
for four points to
be concyclic.
Need to
prove
Theorem- If two points lie on
the same side of an interval,
and the angles subtended at
these points by the interval
are equal, then the two
points and the endpoints of
the interval are concyclic.
Need to
prove
Theorem- Any three
non-collinear points lie on
a unique circle, whose
centre is the point of
concurrency of the
perpendicular bisectors of
the intervals joining the
points.
Need
to prove
Tangents
Theorem- Two
circles touch if
they have a
common tangent
at the point of
contact.
Need to prove
Theorem- The tangent to a
circle is perpendicular to the
radius drawn to the point of
contact.
Don't need
to prove
Theorem- Tangents to a
circle from an external
point are equal.
Need to
prove
Looks like
Birds beak
Need to prove
Don't need
to prove
Theorem- When two
circles touch, their
centres and the point
of contact are collinear.
Theorem- Angle in the alternate segment.
The sail boat
Need to
prove
MOST IMPORTANT
Intersecting Secants
and Chords
Theorem- The square of
the length of the tangent
from an external point is
equal to the product of the
intercepts of the secant
passing through this point.
Need to
prove
Need to
prove
Theorem- The products
of the intercepts of two
intersecting secants to a
circle from an external
point are equal.
Need to
prove
Theorem- The
products of the
intercepts of two
intersecting chords
are equal.