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2 votes
How do I do this? I need answers to 2 decimal places, please. Thanks :)

How do I do this? I need answers to 2 decimal places, please. Thanks :)-example-1

2 Answers

4 votes

Answer: 127.1 cm

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Step-by-step explanation:

Divide the figure so we have a semicircle on the left and a rectangle on the right. The rectangle is 30 by 25. The semicircle has diameter 30.

If we consider a full circle of diameter 30, then its circumference is exactly C = pi*d = pi*30 = 30pi centimeters.

But we only have half a circle, so we cut that in half to get 30pi/2 = 15pi. That's the distance around the curved portion of this diagram. The straight line portions are handled as exactly as you expect.

Add up the distances around the outer edges to get:

15pi+25+30+25 = 15pi+80

The exact perimeter, in terms of pi, is 15pi+80 centimeters.

To get an approximation of this, we can use pi = 3.14 to get

15*pi + 80 = 15*3.14+80 = 127.1 cm

To get a better approximation, use more decimal digits in pi. Or you can let your calculator handle the decimal digits of pi (in other words, use the stored version of it).

User Kilizo
by
5.7k points
4 votes

Step-by-step explanation:

perimeter = 30+(2×25)+(½×3.14×30)

= 30+50+47.1

= 127.1 cm

Area = (25×30)+ (½×3.14×15²)

= 750 + 353.25

= 1.103.25 cm²

User Rswolff
by
5.1k points