12
When you require that degree of accuracy in the answer: no more and no less.
56 square units
3
The decimals with the same number of decimal places are called like decimals. Equivalent decimals are decimal numbers that have the same value. For example, 3.42, 6.05 are like decimals as they have two decimal places. For example, 0.3 and 0.30 are equivalent decimals as they present the same value.
Lots of places
If: (-2, 9) and (-7, -3) is the same distance then the height of the triangle is 13 units and each length of the equilateral triangle is 15.011107 units. Area = 0.5*13*15.011107 = 97.572 square units to 3 decimal places
calculator
4 decimals: 1.0033 3 decimals: 1.003 2 decimals: 1.00
47.50
25.59
3.1415926535897932384626433832795028841971693993751
Divide the base in half and draw the median from the apex. This median is also the altitude and so its length is the required height. Also, since it is the altitude, it forms a right angled triangle. Using Pythagoras on this triangle, the height is 9*sqrt(3)/2.