The length of two chords AB and AC of a circle are 8 cm and 6 cm and ∠BAC=90º, then the radius of circle is

In a regular polygon, the exterior and interior angles are in the ration 1:4.The number of sides of the polygon is

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

If ABC is an equilateral triangle and D is a point on BC such that AD⊥BC, then 

If the circumradius of an equilateral triangle be 10 cm, then the measure of its in-radius 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

In a triangle, if orthocentre, circumcentre, incentre and centroid coincide, then the triangle must be

If the incentre of an equilateral triangle lies inside the triangle and its radius is 3 cm, then the side of the equilateral triangle is