5/18/17 Week 7 Thursday daily sheet:
Area of composite figures/ Word problems on perimeter & area
Daily aims:
 1. I can find the area of composite figures (requiring addition or subtraction).
 2. I can tell when a word problem calls for finding perimeter and when it calls for finding area.
 3. I can solve word problems that involve perimeter and area calculations.
Before lesson
A 40 ft long symmetric hall is shown on the right.
During lesson
10 ft.
10 ft.
1a) REVIEW: What’s its perimeter?
16 ft.
1b) What’s its area?
24 ft.
¾ in.
2 ¾ in.
½ in
1 in.
½ in
2) What’s the area of this composite figure?
D. Stark 4/7/2017
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3) Joan made a pan of brownies in a 9”  13” pan.
Her roommate Pat likes underdone brownies and ate a
4”  4” square out of the middle. How many square
inches of brownie were left after Pat’s snack?
4 in
4 in
9 in
13 in
4) Together we’ll work through a few of the word problems from
pp. 116-117 listed on your homework sheet.
D. Stark 4/7/2017
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Area of composite figures/ Word problems on perimeter & area
Before lesson
A 40 ft long symmetric hall is shown on the right.
1a) REVIEW: What’s its perimeter?
P = 24 + 10 + 10 + 10 + 6 + 16 + 6 + 10 + 10 + 10 +
24 + 16 = 152 ft
KEY
During lesson
Make sure to read the text as well as looking at the
diagram. The entire length of the symmetric hall is
40 ft. so the little horizontal bit on the right is
40 – 24 – 10 = 6 ft. You can find the other lengths
by symmetry.
10 ft.
10 ft.
5/18/17 Week 7 Thursday daily sheet:
Remember perimeter is in regular units.
1b) What’s its area?
area main 40’  16’ piece: A = Lw
= (40)(16)
= 640 ft2
area of each square add-on: A = s2
= 100 ft2
16 ft.
24 ft.
Area:
total area = area main piece + 2(area square bit)
= 640 + 200 = 840 ft2
Remember area is in square units.
D. Stark 4/7/2017
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2) What’s the area of this composite figure?
¾ in.
2 ¾ in.
½ in
1 in.
½ in
Area:
The base of the isosceles (2 sides congruent)
triangle is 1 in + ½ in + ½ in = 2 in.
area rectangle: A = Lw
= (2 ¾)(1) = 2 ¾ in2
area of triangle: A = ½ bh
= ½ (2)(¾)
= ¾ in2
total area = area rectangle + area triangle
= 2 ¾ + ¾ = 3 ½ in2
D. Stark 4/7/2017
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3) Joan made a pan of brownies in a 9”  13” pan.
Her roommate Pat likes underdone brownies and ate a
4”  4” square out of the middle. How many square
inches of brownie were left after Pat’s snack?
4 in
4 in
9 in
13 in
area pan: A = Lw
= (13)(9) = 117 in2
area eaten bit: A = s2
= 42
= 16 in2
Notice that in this case we need to SUBTRACT
one area from the other rather than adding.
total area = area pan – area eaten
= 117 – 16 = 111 in2
4) Together we’ll work through a few of the word
problems from pp. 116-117 listed on your homework
sheet.
See the answer key in the book. Note that I
deliberately assigned only certain problems on this
page.
D. Stark 4/7/2017
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