Finding the area of an isosceles triangle.

Finding the area of a triangle

Let’s look at another problem that involves finding the area of a triangle. This time it will be an isosceles triangle, which is a triangle that has two congruent sides. Remember the formula for finding the area of a triangle is ½ Base x Height

Find the area of an isosceles triangle with sides of 4,4, and 3 units.

Step 1. To find the height I will draw a line straight down from the vertex to the base. I’m using the leg of 3 units as my base.

Step 2. When I draw this line it will form a right angle and two smaller triangles. The measurements of these triangles will be 1.5 and 4 and one missing leg which we will call A

Step 3. I can now use the Pythagorean Theorem to find the missing leg.  So this will become

             A^2 +1.5^2 =4^2

            A^2 + 2.25 = 16

           A^2 = 13.75 then take square = 3.7 so this is my height.

Step 4. Now I have what I need for the equation ½ * 3 * 3.7 = 5.5 units squared

So that is how you find the area of an isosceles triangle. The video works the example problem.

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