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Pre-Algebra Obj. 4a,4c Surface Area
Yesterday we learned… • Surface Area is the amount of exposed AREA on a 3-D object. • Surface Area is always measured in square units, just like AREA is. Can you identify the part of this dresser that is the surface area?
Today… We are going to use our formula sheets to help us find the Surface Area of cubes and cylinders.
Understanding Surface Area Before we get started though… Let’s make sure we have a good understanding of what Surface AREA is.
Understanding Surface Area • Jim painted his shed to blend in with the surroundings. • How would you determine the surface areaof the part of the shed that was painted.
Understanding Surface Area Shelia is frosting a cupcake. What is the surface areaof the part of the cupcake that is being frosted?
Understanding Surface Area • The glass on the Memphis pyramid is being replaced. • How would you determine the surface areaof the part of the pyramid where the glass will be replaced.
Understanding Surface Area • You are wrapping a gift in a rectangular shaped box. • How would you determine the amount of wrapping paper needed to wrap the gift?
Let’s now look at our Formula Sheets. Formula Sheet Surface Area cylinder (lateral) S = 2 rh 3 in 6 in
Guided Practice Surface Area cylinder (lateral) S = 2 rh 1) Find the surface area of the cylinder (without the lids) 3 in 6 in SA = _____ x _____x_____ x _____ = ____________
You Try! What is the surface area of cylinder (without the lids) SA = _____ x _____ x _____ x _____ = ____________
You Try! 1) Find the surface area of cylinder (without the lids) S = 2 rh Radius: 10 ÷ 2 = 5 SA = 2 x 3.14 x 5 x 12 = 376.8 cm²
MCT2 You Try! 2. • What is the surface area of the cylinder • if the lids have been removed? • SA = __________ What is the totalsurface area including the two lids? Total SA = __________
MCT2 You Try! 2. Find the Surface Area (no lids): SA = 2 rh = 2 x 3.14 x 6 x 16 = 602.88 in² Find the Surface Area (with lids): Area of circle = r² = 3.14 x 6² = 113.04 SA = 602.88 + 113.04 + 113.04 = 828.96 in²
Challenge Empty cans were painted (bottoms included) and used as planters to attach to a wall. How would you go about finding the surface areaof the painted part of each can? Did the paint go on the top? Yes or No Did the paint go on the bottom? Yes or No Did the paint go around the side? Yes or No