How To Find The Area Of An Unusual Shape

Slide 1: How to find the Area of this unusual shape 45 55 20 22

Slide 2: This shape is actually 2 rectangles 45 55 20 22

Slide 3: So we need to find the area of each rectangle 45 55 20 22

Slide 4: The blue rectangle is 45 wide by ? long 45 Remember that ? 55 rectangles have the two opposites 20 sides equal. 22

Slide 5: We to have find out ? - the width of the blue rectangle. 45 So that is 55 - 20 ? 55 22 20 35

Slide 6: So the Area of the blue rectangle is 45 X 35 which is: 45 1575 55 20 22

Slide 7: So now we only have to find out the Area of the pink rectangle and add it to the blue rectangle 45 1575 55 20 22

Slide 8: We know the pink rectangle is 22 long by 20 wide so all we have to do is multiply the two numbers. 45 1575 X = 440 55 20 22

Slide 9: So now we have the Area of both rectangles and we need to add them together 1575 440

Slide 10: So the Area of our unusual shape is 45 55 1575 440 20 22 + = 2015

Slide 11: Now try these other shapes by clicking on them 8 13 10 22 8 10 24 20 Practical 15 Application 1 Practical Application 2 36 Practical Application 3

Slide 12: A rectangle and a triangle 20 15 Click here 36 to return to try the Click other here to shapes Remember the area of a check triangle is length X breadth answer divided by 2.  A=lXb 2

Slide 13: What is the area of the blue part of the donut 8 10 Click here Click to return to here to try the check other answer shapes  The formula for the Area of a circle is: A = πr2

Slide 14: So that is 2 circles 10 8 Confused click on this Click picture if you need Click here here to check answer help to return to try the other  shapes

Slide 15: So you have to take away the area of the small circle from the area of the big one. But first find out the radius of the larger circle which is 10 + the radius of the smaller circle (8) 10 8 Click here to return to try the other Click shapes here to check answer  The formula for the Area of a circle is: A = πr2

Slide 16: So add the area of the three rectangles 8 Click here to return to 13 try the other 10 22 or shapes Find the Area of the large rectangle and take away the 24 Area of the smaller inside one. 13 Click here to 22 check answer 10  24

Slide 17: How much will it cost to carpet the lounge room and hallway of this house at $55 per sq.m. 3.5m 5m 1m 2m Click Click here here to to return to check try the answer other shapes 

Slide 18: How much will it cost to tile the kitchen and dining room of this house at $68 per sq.m. 5m 1m 2m Click Click here here to to return to check try the answer other  Kitchen Dining Room shapes The kitchen is 4m by 2.4m

Slide 19: Here are the four walls of a bedroom – How much would it cost to paint them at $3.50 per Sq. M. 4.5m 4.5m 1m 1.7m 2.5m D 2.5m o 1.5m Window 1.8m o r 3.2m 3.2m Click 1.3m here to check 2.5m 2.5m Window 1.5m answer  Help Remember we don’t want to paint the door or windows, so think about how you will do it

Slide 20: How to do it! • Find out the area of the four walls and take away the area of the door and windows • Then multiply the answer by the amount it costs to paint 1 sq. m. • E.g. for wall with door Return to - Area of Area of yellow rectangle blue problem = 4.5 X 2.5 rectangle = 1 X 1.8

Slide 21: 8 Answers Click on the answer you have 13 408 398 480 528 10 22 24 1 1018.29 871.41 817.14 201.14 8 0 20 420 540 300 480 15 3 6 Practical Application 1 $1365.20 $1078.00 $2378.75 $43.25 Practical Application 2 $14.85 $4325.00 $1960.00 $1485.80 Practical Application 3 $117.95 $33.70 $171.85 $350.00

Slide 22: Yes that’s right

Slide 23: Sorry that is wrong – check your workings – try again! 8 13 10 22 8 10 24 20 Practical 15 Application 1 Practical Application 2 36 Practical Application 3