Given that ΔDEF ~ ΔABC. If the area of ΔABC is 9 cm² and area of ΔDEF is 12cm2 , BC = 2.1 cm, then the length of EF is:

O is the centre of this circle. Tangent drawn from a point P, touches the circle at Q. If PQ = 24 cm and OQ = 10 cm, then what is the value of OP? 

What is the area (in sq. units) of the triangle formed by the graphs of the equations 2x+5y-12=0, x+y=3 and y = 0?

In a triangle, if three altitudes are equal, then the triangle is 

The side QR of an equilateral triangle PQR is produced to the point S in such a way that QR = RS and P is joined to S. Then the measure of ∠PSR is

ABC is a triangle in which DE || BC and AD: DB = 5: 4. Then DE: BC is

If C₁, C₂ be the centres of rwo circles and r₁, r₂ be the respective radii such that the distance between the centres is equal to the sum of the radii of the two circles, find the number of common tangents.

AB is a diameter of a circle with centre O. The tangents at C meets AB produced at Q. If ∠CAB = 34°, then measure of ∠CBA is