In every case, you're finding the surface area of a rectangular prism. That area is the sum of the areas of the 6 rectangular faces. Since opposite faces have the same area, the formula can be written
... S = 2(LW +WH +HL)
The number of multiplications can be reduced if you rearrange the formula to
... S = 2(LW +H(L +W))
where L, W, and H are the length, width, and height of the prism. (It does not matter which dimension gets what name, as long as you use the same number for the same variable in the formula.)
When you're evaluating this formula over and over for diffferent sets of numbers, it is convenient to let a calculator or spreadsheet program do it for you.
1. S = 2((5 cm)(5 cm) +(5 cm)(5 cm +5 cm)) = 2(25 cm² +(5 cm)(10 cm))
... = 2(25 cm² + 50 cm²) = 150 cm²
2. S = 2(12·6 + 2(12+6)) mm² = 2(72 +36) mm² = 216 mm²
3. S = 2(11·6 + 4(11 +6)) ft² = 2·134 ft² = 264 ft²
4. S = 2(10·4 +3(10 +4)) in² = 164 in²
Answer:
187 paving stones are needed
Step-by-step explanation:
Given
Paving stone
Compound
Required
Number of wires to cover the compound
Area is calculated as:
For the paving stone, we have:
Convert cm to m
For the compound, we have:
Divide the area of the compound by the area of the paving stone
Answer:
the value of x is 260 according to the reflection of triangle
81x^2 - 4y^2 Note this is the difference of 2 perfect squares
a^2 - b^2 = (a + b)(a - b)
so here we have a = 9x and b = 2y
and our factors are
(9x + 2y)(9x - 2y)
the dimensions are 9x + 2y and 9x - 2y