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
3/45 = 20/x...3 in to 45 seconds = 20 in to x seconds
cross multiply
(3)(x) = (45)(20)
3x = 900
x = 900/3
x = 300...300 seconds (or 5 minutes)to fill the tub with 20 inches
Answer:
cos(400)
Step-by-step explanation:
Useful things:
Cofunction identity: sin(x)=cos(90-x)
Sine and cosine have period of 360 degrees.
So sin(50)=cos(40) by cofunction identity.
Since cosine has period of 360 degrees then cos(40)=cos(360+40).
That simplifies to cos(400).
Answer: B ( 2,9) .
Step-by-step explanation:
Answer:
12.8 cm
Step-by-step explanation:
Radius of the can is 8 cm and height is 20 cm.
It is given that after painting his porch Jamil has 
of a can of paint remaining. So, first we need to find the total amount of paint in the can.
Total amount of paint in the can is 
So, paint in the can 
Now of the can is 
cubic cm.
Now, let the height of the smaller can be <em>h</em> cm.
Radius of the smaller can is 5 cm.
As, the paint is poured into the smaller can the volume of both the cans will be same.
Hence, height of the smaller can to hold the paint must be 12.8 cm.
