# IGCSE Mathematics Paper-1: Specimen Questions with Answers 106 - 109 of 324

## Question 106

## Question 107

### Write in Short

Short Answer▾The diagram shows a regular octagon and a rectangle. Calculate the values of .

### Explanation

Here, octagon is regular.

So, we can find it’s exterior angle by using the formula , where n = number of sides.

In octagon number of sides = 8, so **exterior angle** =

So, as shown in figure, its **interior angle** .

Now, for angle :

(I) As shown in figure:

**OR**

(II) As shown in figure, total angle is , so

## Question 108

### Write in Short

Short Answer▾Choose from the symbols to complete the following statements.

(a)

(b)

### Explanation

Here,

(a) First statement is

- So, and . So, .
- So,

(b) Second statement is .

- So,
- So,

## Question 109

### Write in Short

Short Answer▾(a) (i) Write both numbers in the calculation above correct to one significant figure.

(ii) Use your answer above to estimate the value of the calculation.

(b) Find the value of the calculation correct to three significant figures.

### Explanation

Here,

(a) (i) Number 782 correct to one significant figure will be: because in the number after 7 there is 8 which is greater than 5 so 7 will be increased by 1 and be **8** which is significant figure while both 0s are at left side of decimal point which are not significant.

Number 44 correct to one significant figure will be: **40**, where **4** is significant figure while 0 is at left side of decimal point which is not significant.

So,

(ii) Answer of will be **20** which is estimate value of

(b) Calculation of will be: 17.77.

Now, 17.77 correct it to three significant figures: **17.8** where 1, 7 and 8 are significant.