A ladder on the platform of a fire brigade van can be elevated at an angle of 70°

Let the maximum height from the ground upto which the ladder can reach be h meters.

Using the concept of trigonometry, we have:

sin 70° = opposite/hypotenuse

or, hypotenuse = opposite/sin 70°

or, hypotenuse = h + 2/0.94 (as the platform is 2m above the ground)

or, hypotenuse = (h + 2)/0.94

Now, the length of the ladder is given as 20m, so we can write:

hypotenuse = 20/cos 70° (using the concept of trigonometry)

or, (h + 2)/0.94 = 20/cos 70°

or, h + 2 = 0.94 x 20 / cos 70°

or, h = 0.94 x 20 / cos 70° – 2

Evaluating this expression using a calculator or by looking up the value of cos 70° as 0.342, we get:

h ≈ 21.76 meters (rounded to two decimal places)

Therefore, the maximum height from the ground upto which the ladder can reach is approximately 21.76 meters.