Surface Area Definition Surface Area is the total

Surface Area

Definition • Surface Area – is the total number of unit squares used to cover a 3 -D surface.

Find the SA of a Rectangular Solid A rectangular solid has 6 faces. They are: Top Right Side Front Top Bottom Front Back Right Side Left Side We can only see 3 faces at any one time. Which of the 6 sides are the same? Top and Bottom Front and Back Right Side and Left Side

Surface Area Front: 5 cm x 4 cm = 20 cm 2 Back: 5 cm x 4 cm = 20 cm 2 Right Side: 2 cm x 4 cm = 8 cm 2 Left Side: 2 cm x 4 cm = 8 cm 2 Top: 5 cm x 2 cm = 10 cm 2 Bottom: 5 cm x 2 cm = 10 cm 2 Add up all the sides up: 76 cm 2

Surface Area of a Rectangular Solid Top Right Side Front We know that Each face is a rectangle. and the Formula for finding the area of a rectangle is: A = lw Steps: Find: Area of Top Area of Front Area of Right Side Find the sum of the areas Multiply the sum by 2. The answer you get is the surface area of the rectangular solid.

Find the Surface Area of the following: Find the Area of each face: 12 m Top 2 Top: 12 m x 5 m = 60 m 2 Top and Bottom: 2 x 60= 120 m 5 m Top 2 Front: 12 m x 8 m = 96 m 2 Front and Back: 2 x 96= 192 m Right Side 8 m Front 5 m 8 m 12 m 2 2 2 Sum = 120 m + 192 m + 80 m = 392 m 2 Right Side 2 8 m Right = 8 m x 5 m = 40 m 2 Right and Left: 2 x 40= 80 m 5 m The surface area = 392 m 2

Find the Surface Area Using the FORMULA Rectangular Prism SA = 2(lw) + 2(wh) + 2(lh) LOW WHO LOH PLUG INTO FORMULA 2(6 x 4) + 2(4 x 14) + 2(6 x 14) 2(24) + 2(56) + 2(84) 48 + 112 + 168 = H= 14 cm W= 4 cm L= 6 cm The surface area of this 2 rectangular solid is 328 cm.

Nets • A net is all the surfaces of a rectangular solid laid out flat. Back Top 8 cm Front Left Side Top 8 cm Right Side Front 8 cm 5 cm 10 cm Bottom 10 cm 5 cm

Find the Surface Area using nets. 80 Back Top 8 cm Front Right Side 40 Left Side 50 Top 8 cm 40 Right Side 5 cm 10 cm Each surface is a rectangle. A = lw Find the area of each surface. Which surfaces are the same? Find the Total Surface Area. 80 Front 50 Bottom 10 cm What is the Surface Area of the Rectangular solid? 340 cm 2 8 cm 5 cm

• Surface of a Cube: 6 a 2 » How many sides are there? 6 sides » Area of one side is a x a = a 2 a • 6 (32) = 6(9) = 54 cm 2 Area of one side is 3 x 3 = 9 There are 6 sides: 6 x 9 = 54 3 cm