3.2 Evaluating Formulas

3.2 Evaluating Formulas

​We have learned that the area of a rectangle is given by: Area = length x width

If we use A to represent area, l to represent length and w to represent width, we get A = lw

Connecting 2 or more variables in this way is called a formula. When we know the values of l and w, we can find the value of A using substitution.

​Formulas

Multiple Choice

Try It: The perimeter, P meters, of a rectangular field with dimensions l meters by w meters, is given by the formula: P = 2( l + w ). Find the perimeter of a rectangular field whose dimension is 60 meters by 45 meters.

• 210 meters
• 205 meters
• 220 meters
• 2100 meters

Multiple Choice

Try it a: Given the formula $$D=\frac{1}{2}n\left(n-3\right)$$ , find the value of D when n = 5

• 5
• 10
• 15
• 20

Multiple Choice

Try it b: Try it a: Given the formula $$D=\frac{1}{2}n\left(n-3\right)$$ , find the value of D when n = 12

• 54
• 72
• 36
• 48

Multiple Choice

Try it: If $$s=\frac{v^2-u^2}{2a}$$ , find the value of s when u = 3, v = 12 and a =6.

• $$11\frac{1}{4}$$

• 24

• 22.5

• 48