For what value of k, system of equations 5x + 2y = k, 10x + 4y = 3 has infinitely many solutions?

If the simple interest and compound interest at the same rate of certain amount for 2 years are Rs. 400 and Rs. 420 respectively, then the rate of interest is ;

If $\sqrt{5} \tan \theta=5 \sin \theta$, what is the value of $\left(\sin ^{2} \theta\right.$ $\left.-\cos ^{2} \theta\right) ?$

If the height of a cone is 15 cm and its volume is 770 cm³, find the radius of its base?

$\left(\pi=\frac{22}{7}\right)$

$\frac{\sin \theta}{1+\cos \theta}+\frac{1+\cos \theta}{\sin \theta}=?$

The number of diagonals in an octagon is

The radius of a cycle wheel is 35 cm. How many revolutions, will it make to cover a distance of 1.1 km?

$\left(\right.$ Take $\left.\pi=\frac{22}{7}\right)$

If the points (h, o), (a, b) and (o, k) lie on a line, then?

If A + B = 90° then, $\sqrt{\frac{\tan A \cdot \tan B+\tan A \cdot \cot B}{\sin A \cdot \operatorname{secB}}-\frac{\sin ^{2} B}{\cos ^{2} A}}=?$