Forum

Circles

Two circles with centres O and O′ intersect at two points A and B. A line PQ is drawn parallel to OO′ through A(or B) intersecting the circles at P and Q. Prove that PQ = 2 OO′.

06/11/2024

Mathematics

9th

Circles

A quadrilateral ABCD is inscribed in a circle such that AB is a diameter and ∠ADC = 130º. Find ∠BAC.

06/11/2024

Mathematics

9th

Circles

A chord of a circle is equal to its radius. Find the angle subtended by this chord at a point in major segment

06/11/2024

Mathematics

9th

Circles

The circumcentre of the triangle ABC is O. Prove that ∠OBC + ∠BAC = 90º.

06/11/2024

Mathematics

9th

Circles

If a pair of opposite sides of a cyclic quadrilateral are equal, prove that its diagonals are also equal.

06/11/2024

Mathematics

9th

Circles

If a line is drawn parallel to the base of an isosceles triangle to intersect its equal sides, prove that the quadrilateral so formed is cyclic.

06/11/2024

Mathematics

9th

Circles

If BM and CN are the perpendiculars drawn on the sides AC and AB of the triangle ABC, prove that the points B, C, M and N are concyclic.

06/11/2024

Mathematics

9th

Circles

Two chords AB and AC of a circle subtends angles equal to 90º and 150º, respectively at the centre. Find ∠BAC, if AB and AC lie on the opposite sides of the centre.

06/11/2024

Mathematics

9th

Circles

On a common hypotenuse AB, two right triangles ACB and ADB are situated on opposite sides. Prove that ∠BAC = ∠BDC

06/11/2024

Mathematics

9th

Circles

O is the circumcentre of the triangle ABC and D is the mid-point of the base BC. Prove that ∠BOD = ∠A.

06/11/2024

Mathematics

9th