Step-by-step explanation: We start with the 10,000 feet original height. From there, we can take 2,000 feet per minute and multiply it by 10 minutes. That gets us 20,000 feet. Add 20,000 to our original 10,000 and we get 30,000.
The sum of the angles in any triangle is 180 degrees. If one of the three angles is 90 degrees (a right angle) the the sum of the other two angles is 90 degrees. Therefore each of the other two angles must be acute.