**surface area**. For my blog I was assigned to do

**question 1 (chapter 1.3) in the homework book**.

**Key Ideas Review:**

**1.**Complete the chart below, using the first row as a sample. Show your answer to the nearest tenth.

***NOTE: The surface area for the triangle was supposed to be 1.5m (squared)**

**Calculations:**

**Square**: A = l x w

= 10 x 10

= 100 cm (squared)

**Rectangle**: A = l x w

= 30 x 22.5

= 675 cm (squared)

**Circle**: A = pi x r squared

= pi x (15 x 15)

= pi x 225

= 706.9 cm (squared)

**Rectangular Prism**: A = 2(lw) + 2(lh) + 2(hw)

= 2(25 x 12) + 2( 25 x 12) + 2( 12 x 12)

= 2(300) + 2(300) + 2(144)

= 600 + 600 + 288

= 1488 cm (squared)

**Cylinder:**A = 2 [(pi)(r) squared] + 2 (pi)[( r x h)]

= 2 [(pi) (4 x 4)] + 2[ (pi) (4 x 15)]

= 2 (pi) (16) + 2 (pi) (60)

= 2 (50.3) + 2 (188.5)

= 100.6 + 377

= 477.6 cm (squared)

*** NOTE: I rounded the answer for pi x 16 and pi x 60 to the nearest tenth which is why my answer is 0.1 higher.**

**Triangle**: A = 1/2 b x h

= 1 x 1.5

= 1.5 cm (squared)

**My Examples:**

**Square**: One side of a box: 20 cm by 20 cm

**A = l x w**

**= 20 x 20**

**= 400 cm (squared)**

**Rectangle:** A wooden door: 35 cm by 23

**A = l x w**

**= 35 x 23**

**= 805 cm (squared)**

**Circle**: One side of a car tire: Radius of 17 cm

**A = pi x r squared**

**= pi x (17 x 17)**

**= pi x 289**

**= 907.9 cm (squared) nearest tenth**

**Rectangular Prism:** Math textbook: l= 7 cm w= 8 cm h= 5 cm

**A = 2(lw) + 2(lh) + 2(hw)**

**= 2( 7 x 8) + 2(7 x 5) + 2(5 x 8)**

**= 2 (56) + 2(35) + 2(40)**

**= 112 + 70 + 80**

**= 262 cm (squared)**

**Cylinder**: Hairspray Can: 13 cm high and 6 cm for radius

**A = 2 [pi r (squared)] + 2 [pi (r x h)]**

**= 2 [pi (6 x 6)] + 2 [pi (6 x 13)]**

**= 2 (pi x 36) + 2 (pi x 78)**

**= 2 x 113.1 + 2 x 245**

**= 226.2 + 490**

**= 716.2 cm (squared)**

***NOTE I rounded the answer for**** pi x 36 and pi x 78 to the nearest tenth.**

**Triangle:** End of a Toblerone Package: 4 cm for base and 2.5 cm high

**A = 1/2 b x h**

**= 2 x 2.5**

**= 5cm (squared)**

**Thank you for reading my blog and please don't forget to COMMENT !**

Good job MaryJane. I like your colours and the way you did the chart. I didn't find any mistakes so congratz.

ReplyDeleteGOOD JOB MARYJANE ! I liked your use of colours and the way you gave real examples . Wonderful Job on the table , it is clear to see that you put in a lot of time and effort in making this blog post. Good Job Maryjane!

ReplyDelete