AB is a diameter. C is a point on the circle.
Prove that $\angle ACB = 90^\circ$
A, B, C and D are points on the circle that form a quadrilateral.
Prove that
$\angle ABC + \angle ADC = \angle BAD + \angle BCD = 180^\circ$
A, B, C and D are points on the circle that form a quadrilateral.
Prove that
$\angle ABC + \angle ADC = \angle BAD + \angle BCD = 180^\circ$
A, B and C are points on the circle. O is the centre of the circle.
Prove that $\angle AOB$ is twice $\angle ACB$
A, B and C are points on the circle. O is the centre of the circle.
Prove that $\angle AOB$ is twice $\angle ACB$
A, B, C and D are points on the circle.
Prove that $\angle ACB = \angle ADB$.
A, B, and C are points on the circle. The line AD is tangent to the circle.
Prove that $\angle DAC = \angle ABC$
AB is a chord. D lies outside the circle on AB. C is a point on the circle. O is the centre of the circle.
Prove that $\angle AOC$ is twice $\angle CBD$
A and B are points on the circle. The tangents to the circle at the points A and B meet at C.
Prove that the length AC is equal to the length BC
