Prove that the intercept of a tangent between two parallel tangents to a circle subtends a right angle at the centre.

What is the distance between two parallel tangents to a circle of radius 5 cm?

What is the distance between two parallel tangents of a circle of radius 4 cm?

Prove Equal chords of a circle subtend equal angles at the centre.

Prove The angle between two tangents to a circle may be 0^(@) .

Prove Equal chords of congruent circles subtend equal angles at the centre.

Two parallel tangents of a circle meet a third tangent at points P and Q. Prove that PQ subtends a right angle at the centre.

Prove that the portion of the tangent to an ellipse intercepted between the ellipse and the directrix subtends a right angle at the corresponding focus.

Prove that equal chords of congruent circles subtend equal angles at their centre.

Prove that equal chords of congruent circles subtend equal angles at their centre.

If the chord of contact of the tangents drawn from the point (h , k) to the circle x^2+y^2=a^2 subtends a right angle at the center, then prove that h^2+k^2=2a^2dot