The length of the common chord of two circles of radii 30 cm and 40 cm whose centers are 50 cm apart is (in cm) 

ΔABC is similar to ΔDEF. Length of AB is 18 cm and  length of the corresponding side  DE is 10 cm. What is the ratio  of Perimeter of ΔABC : Perimeter of ΔDEF?

 If $$ {x=7-4\sqrt{3}}$$ find the value of $$ {\sqrt{x}+{1\over {\sqrt{x}}}}$$.

In ΔABC, AB = AC and ∠B = 40 °, find the value of ∠A.

In a circle, PQ is diameter, RS is chord of length equal to radius of circle. PR and QS when produced intersect at point T. Find the ∠PTQ?

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

If two complimentary angles are in the ratio of 4:5, find the greater angle.