The original question was: I am a Physics teacher wanting to measure the height of a rocket. 3 measurers are standing at the corners of an equilateral triangle standing on flat ground. Physicist: If the rocket doesn’t arch too much, then you can find the maximum height of a rocket by just standing around in a field and measuring the largest angle between the horizon and the rocket. If somehow you knew the north-south and east-west position of the rocket at the top of its flight, then you’d only need one angle measurement. But, in the special case of an equilateral triangle it’s not terrible.