The volume of a cubical solid is 10368 cm³. If its dimensions are in the ratio 3 : 2 : 1, find the cost of polishing its total surface at the rate of ₹ 2.50 per m².

Squares, each of side 6 cm are cut off from the four corners of a sheet of tin measuring 42 cm by 30 cm. The remaining portion of the tin sheet is made into an open box by folding up the flaps. Find the capacity of the box formed.

If 3 cos A = 4 sin A: find the value of :

4 cos² A - 3 sin² A + 2

If 4 cos² A - 3 = 0 and 0° ≤ A ≤ 90°; find:

(i) angle A

(ii) cos 3 A

(iii) tan² A + cos² A