Grade 9, Math 9 Surface Area January 15, 2016 aaronq2015 2 Comments This is our composite shape. The measurements of the small rectangle is 4 by 3 by 18 The measurement of the large rectangle is 7 by 7 by 25 This is the front of our large rectangle and its the same on the other side. The measurements for this side is 7 time 7 so you multiply the two to get 49,but then you multiply 49 by 2 because there is 2 of the same sides. Which is 98cm2 This is the top of the large rectangle and the measurements of the top is 7 by 25. 25 by 7 is 175 and since there are 4 other sides that are the same you can times 175 by 4 to get 700. So in total this shape’s surface area is 798cm2 The measurements of the front of this smaller rectangle is 4 by 3. 3×4 is 12 and since there are 2 side you times this by two. 24cm2! This side of this small rectangle measurements is 4 by 18. It the answer is 72 and 72×2 is 144cm2 The top and bottom of this shapes measurements are 3 by 18. 3×18 is 54 and 54×2 is 108cm2. In total this shape is 24+144+108 is 276cm2. Since the top of this shape is on the bottom of the large rectangle you add the large rectangle to the small to get 798+276=1,074 and now you just subtract the top and the bottom of the small rectangle because of the space in between the both shapes. So 1,074-108=966cm2. The total surface area for the whole shape is 966cm2