A boat is being rowed away from a cliff 270 m high. From the top of the cliff, the angle of depression of the boat changes from 60° to 45° in 2 minutes. What is the speed of the boat?
According to the figure above: tan 45° = 270/(a + b) ⇒ 1 = 270/(a + b) ⇒ a + b = 270 Also, tan 60° = 270/a ⇒ √ 3 = 270/a ⇒ a = 270/ √ 3 ⇒ a = 90√ 3 = 155.8 ∴ b = 270 - 155.8 = 114.2 ⇒ The boat covers a distance of 114.2 m in 2 minutes. ∴ Speed of the boat = (114.2 x 60)/(2 x 1000) km/h = 3.4 km/h
70.14% of 799.95 - 240.12 = ? + 40.17% of 299.95
(13.13 × 32.98) + 20.15% of 649.99 = ? + 122.34
3 √2197.08 × 5.15 + 13.302 = √675.99 + ?
(1331)1/3 x 10.11 x 7.97 ÷ 16.32 =? + 15.022
30.11% of 149.99 + √195.97 ÷ 7.02 = ?
2720.03 ÷ 79.98 x 39.9 = ? + 40.32
? = 44.78% of 839.91 – 48.12% of 774.89 + 55.77% of 1024.85
96.03% of √225.02 × 14.98 = ? + 19.98
{(√2305) % of 74.69} × 15.21 - 27.89 × 44.88 + 45.12% of 2399.87
766/51 ÷ 387/42 × 121/13 = ?
