If in a triangle, the orthocenter lies on vertex, then the triangle is 

In ΔABC, ∠C=90° and CD is perpendicular to AB at D. If AD/BD=, then AC/BC=?

The sum of all interior angles of a regular polygon is twice the sum of all its exterior angles.  The number of sides of the polygon is

X and Y are centres of circles of radius 9 cm. and 2 cm respectively XY=17 cm. Z is the centre of a circle of radius r cm which touches the above circles externally. Given that - ∠xzy = 90^o the value of r is -

Find the second diagonal of a rhombus when it’s first diagonal length is 12 cm and its side is 10 cm?

In ΔABC, AB=c cm, AC= b cm and CB=a cm, If  ∠A=2 ∠B, then which of the following is true?

If there are four lines in a plane, then what cannot be the number of points of intersection of these lines? 

If the area of a circle is 9π sq.cm then it circumference is