DO NOW Homework: –Perimeter, area & circumference Day 1 Wkst –Midterms next Tuesday & Wednesday Warm-Up: What formulas do you remember for perimeter, area or circumference? Write as many as you can remember

MARCH 17, 2014 Today’s Lesson: Perimeter, Area, & Circumference

Think about it… What is perimeter? –PeRIMeter: The distance around a figure.

Area of a triangle 5cm 3cm 4cm A = 1/2bh = 1/2(4)(3) = 6cm 2 Do you remember the formula? What is the perimeter of the triangle?

Area of a rectangle A = bh = 4x2 = 8in 2 Do you remember the formula? What is the perimeter of the rectangle?

Area of a square A = bh = 3x3 = 9in 2 Do you remember the formula? What is the perimeter of the square?

Area of a parallelogram 7 cm Area = bh = (7)(4) = 28 cm 2 Perimeter = = 24cm h = 4 cm 5cm Do you remember the formula?

Area of a trapezoid 10 cm 5 cm h = 4 cm Do you remember the formula?

What about pi? (used when we talk about circles) What approximate number do we often use for pi? –3.14 –Pi is really a nonterminating decimal that starts as …

Area of a circle Do you remember the formula?

Do you remember? What is the special word that refers to the perimeter of a circle?

Circumference Formula: What does the d stand for? –Diameter! Diameter is the distance across the circle –What if you don’t know the diameter? If you know the radius, you can double it! –The radius is the distance halfway across the object

Circumference of a circle

HINT!! What is a good strategy to use when doing problems that involve perimeter, circumference, or area? –Draw a picture!

You Try 1. Mr. Bill’s back yard is in the shape of a rectangle. It took him 600 feet of fence to enclose in his back yard. If the length of the yard is twice as long as the width, what are the dimensions of Mr. Bill’s yard?

#1 - Answer length = 200 feet width = 100 feet

You Try 2. A bicycle tire has a diameter of 24 inches. How far does the bike travel, in inches, when the tire completes 1 revolution?

#2 - Answer inches

Think about it… What is area? –Area: The measure of the region that is inside a closed plane figure.

You Try 3. A package containing a swivel stake and a 10-foot dog chain claims that it gives the dog more room to play than a 10-foot square pen. Is this a true statement and if so, how much more room does it allow the dog to play?

#3 - Answer circle = 314 ft 2 rectangle = 100 ft 2 Yes, difference = 214 ft 2.

You Try 4. Mr. Santiago bought a rug with an area of 2500 square inches. Will the rug fit in the front hall, which is 48 inches by 60 inches?

#4 - Answer The area of the hall is 2880 ft 2 so it will fit if the dimensions match okay. If the rug is 50 by 50, it will not fit.

Composite Figures You may have to look at the individual areas then add or subtract to find the answer. What is the area of the “dark blue” region? 8cm 16 cm 8 cm 6 cm

What is the area of the “dark blue” region? Area blue = Area of Rectangle – Area of Triangle = (8 x 16) – (½ x 8 x 6) = 128 – 24 = 104 cm 2 8cm 16 cm 6 cm 8cm

Composite Figures Find the area of this polygon 10 cm 5 cm 2 cm 6 cm

Graph and find the area

Connections to EOG Assessment: A square room with an area of 324 square feet is tiled using square tiles with a side length of 1 foot. How many tiles line each wall of the room? A) 17 B) 18 C) 19 D) 20