There are three taps of diameter 2 cm, 3 cm and 4 cm, respectively. The ratio of the water flowing through them is equal to the ratio of the square of their diameters. The biggest tap can fill an empty tank alone in 81 min. If all the taps are opened simultaneously, then how long will the tank take (in min) to be filled?

AB is a chord of a circle in minor segment with center O.C is a point on the minorarc of the circle between the points A and B. The tangents to the circle at A and B meet at the point P. If ∠ACB = 102⁰ , then what is the measure of ∠APB?

if x+y =3 and $${1\over x}+{1\over y}= -{3\over 10}$$ then the value of (x²+y²) is :

Simplify the following expression.

$${\left({375+125} \right)^2-\left({125-375} \right)^2}\over 375×375-125×125$$

Find the value of

 sin⁴30⁰ + cos⁴30⁰ – sin25⁰cos65⁰-sin65⁰cos25⁰

The value of $$\left({sin37^0cos53^0+cos37^0sin^0} \right)-\left({4cos^237^0-7+4cos^253^0\over tan^247^0+4-cosec^243^0} is \right)$$

if x⁴+y⁴+x²y²=21 and x²+y²-xy=7, then what is the value of  $${x\over y}+{y\over x}=?$$

if 3sin²θ – cosθ-1=0, 0⁰< θ<90⁰, then what is the value of cot θ + cosec θ?