Perimeter/area Flashcards Preview

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Flashcards in Perimeter/area Deck (14):
0

Define a perimeter:

A perimeter is the length of the outline of a geometrical figure.

1

How do you calculate the perimeter of a square?

4xs (s is short for side)
Ex:s=5
5x4
20

2

How do you calculate the perimeter of a rectangle?

There are three methods:
-h+h+w+w (h is short for height, w is short for width)
-hx2+wx2
-(h+w)x2
Ex:h=4 w=5
(4+5)x2
9x2
18

3

Perimeter of a square of s=6?

6x4
24

4

Perimeter of a rectangle h=7 w=10?

(7+10)x2
17x2
34

5

Define area:

Area is all the part that is inside the geometrical figure.

6

How do you calculate the area of a square?

sxs
Ex:s=5
5x5=25

7

How do you calculate the area of a rectangle?

hxw
Ex:h=6 w=5
6x5=30

8

What is pi ( pronounciation: pie)?

Pi is named after the greek letter pi. In maths, pi is equal to ~3.14.Actually, it is impossible to say exactly what pi is equal to since the digits go on for ever with no repetition at all. The first digits are 3.14159265358...
Pi is used for a lot of things, but mainly for measuring the perimeter and area of circles.
The first people to use it were the Greeks.

9

Define the radius of a circle:

The radius is the line that goes from O to the edge of the circle.The radius itself is written r. The measure of the radius is written as R.

10

Define a chord in a circle.

A chord is the line that goes from one edge of the circle to the other.

11

Define the diameter in a circle:

A diameter is the longest chord, it passes by O and is exactly the double of the radius.

12

How do you measure the perimeter of a circle?

Pi x r x 2
Ex: r=5
Pi x 5 x 2
Pi x 10 This is the exact value.
You cannot get closer to the exact value.
3.14x10
31.4 This is the approximate value.

13

How do you measure the area of a DISK (not a circle!)

Pi x (r squared)
Ex: r=5
Pi x (5x5)
Pi x 25 This is the exact value.
3.14x25
78.5 This is the approximate value.