1. 5 CM 4 CM Calculation Area = Length times Width (lw or l x W) Note Length of a rectangle is always the longest side

2. The previous rectangle can be split into 2 equivalent right triangles What do you think the area of each triangle is relative to the rectangle?

3. Area of each triangle will be half the area of a rectangle which is l x w divide by 2 Or 5 x 4 divide by 2 = 10 cm 2 5 CM 4 CM

4. When we look at a triangle by itself we have a base = 5 and height = 4 Therefore we don’t use length and width like a rectangle. Formula changes from to Or 5 x 4 divide by 2 = 10 cm 2 5 CM 4 CM Base Height

5. What if the triangle is not a right angle triangle? How do I find height? Height is the length of the perpendicular line from one vertex to the base 5 CM 4 CM Formula changes from Or 5 x 4 divide by 2 = 10 cm 2

6. Area of triangle is still ½ the area of the rectangle it forms.

7. You can Use the Pythagorean Theorem to find height if you are given length of rectangle or square base and length of one of the sides 2.5 CM 4.72 2 = 2.5 2 + b 2 22.28 = 6.25 + b 2 22.28 – 6.25 = 6.25 + b 2 – 6.25 16.02 = b 2 √16.02 = b 4 = b 4.72 cm b cm

8. FORMULA SURFACE AREA OF CIRCLE π r 2 = 3.14 x 2.5 2 = 19.625 cm 2 2.5 cm Radius (r) C