61. A fountain pen with a cylindrical barrel of diameter 2 cm and height 10.5 cm , filled with ink, can write 3300 words. How many words can be written with that pen using 100 ml of ink? (Take \( 1 \mathrm{cc}=1 \mathrm{ml} \) ) \( \begin{array}{ll}\text { (a) } 40,000 & \text { (b) } 30,000\end{array} \)

Find equation of straight line through \( (-1,4) \) and perpendicular to the line passing through \( (3,0) \) and \( (1,-2) \).

In a right triangle, the lengths of the legs are given as 12 units and 5 units. Use the Pythagorean theorem to find the length of the hypotenuse.

Find equation of straight line through \( (-1,4) \) and perpendicular to the line passing through \( (3,0) \) and \( (1,-2) \).

6. ABCD is a quadrilateral, and AC and BD are its diagonals. Is \( \mathrm{AB}+\mathrm{BC}+\mathrm{CD}+\mathrm{DA}>\mathrm{AC}+\mathrm{BD} \) ? 7. ABCD is a quadrilateral and \( O \) is any point in its interior in the given figure Show that \( A B+B C+C D+D A<2(O A+O B+O C+O D) \).

23. Find the equation of a line. Whoso intercepts on \( x \) and \( y \) axis are 4 and -6