Surface Area

## Finding the perimeter of a given area of a circle.

#### Question: A square has an area of 35 squared centimentres. What is the measure of its perimeter.

Find the area of the given shape.

First way: Finding the area of the whole shape including the missing shape.. Then subtract the area of the missing shape from the whole shape to get the area of the given shape.

Second Way:

## Sunday, December 2, 2012

### Math Test, Question # 1

Question:
A car uses fuel at a rate of 10.2 L/ 100 km while travelling at 90 km/h. At this rate of fuel consumption, how many litres of fuel would the car use if it travels 480 km? Express your answer to the nearest tenth of a litre.

This is how I solved this question:

My simple sentence answer:
The car will use 49.0 L of fuel if it travels 480 km.

### Textbook Pg. 81 #31

#### a) 15 cm, 12 cm, 10 cmb) 9.3 cm, 11.4 cm, 7.5 cm

The area of the triangle is 59.8 square cm.

#### b) 9.3 cm, 11.4 cm, 7.5 cm

The area of the triangle is 34.7 square cm.

## 2. In a cold storage chamber, the temperature drops 5.2C every 10 minutes. If the temperature is initially 19C, what is the temperature in the chamber after 1½ hours?

### Important things we know :

5.2°C down every 10 minutes. (x9 = 90 minutes)
1½ hours  90 Minutes (90 ÷ 10 = 9)
Temperature is 19°C

19°C - (5.2°C x 9)    = 19°C - 46.8°C
= -27.8°C
Therefore, the temperature in the cold storage chamber after 1½ hours is, -27.8°C

### Math Test:Answering #4

4.The figure below is composed of seven congruent squares. The area is 43.75cm2. Calculate its perimeter.

A=Area
P=Perimeter

What We Know:
A=43.75cm2
7 congruent squares
P=14 congruent segments

Answer:
43.75cm2/7 =A of ONE square
=6.25cm2

square root of 6.25cm2=ONE side of small square
=2.5cm

2.5cmx14=A of shape
=35cm

Perimeter of the shape is 35cm.