Example 1:In this example the sides of the rectangle are 4 units by 3 units. The formula for a rectangle is A = l * w: 4*3=12Area = 12 units squared[br]Example 2:If you are given the measurements of the base and height of a triangle you can use this formula.[img width=75,height=27]https://lh3.googleusercontent.com/5iUad5mdke0Z6FCLkLMBHKWRVxkZgvPs5-omKfwa93VAUVFRFwmF74Xv-zBd9de9SfgLskAGoS2kXU7lZiFsnIOlBf-plKTOiq2m5WzzASfTZ0RNakPT3W1_a-H7JiKUZcxG971z[/img]If you don't have those measurements and the triangle is on a graph you can solve it like this:First you have to find the side lengths of the triangle. You can find the side lengths of a triangle by finding the rise over run between two of the points. From point A to B you have to go over 6 and down 1, so you would plug this number into the area formula of a triangle. [br]a=½*bha=½*(1)(6)AB=3Continue this process for the other two sides. BC: A=½*(4)(5)BC=10[br]CA: A=½*(1)(5)CA=2.5[br]Next find the total area surrounding the triangle. In this example this area is represented by a blue box. Using the formula that we learned in the previous example find the area of the square. L*W5*6=30[br]Now take the total area of the shape (30) and subtract the smaller areas from it. 30-2.5-10-3=14.5This means that the area of the triangle is 14.5 units squared[br]