# IGCSE Mathematics Paper-1: Specimen Questions with Answers 134 - 136 of 175

## Question number: 134

### Write in Short

A square ABCD has two diagonals, O is center. Angle ODA = . Calculate angle OAD.

### Explanation

Here,

As we can see in the figure AC and BD are intersecting lines in square.

Angle ADO = , as we know angle made by intersecting of diagonal is so angle AOD =

Now, in any triangle addition of all angles will give

So, in

.

## Question number: 135

### Write in Short

In the diagram, and a line LM passing through point D. Angle . Find the angle LDB, CDM and ADL.

### Explanation

Here, and a line LM passing through point D.

Now, Angle is given.

- So, angles BDM and ADL are
**vertical angles**as shown in figure, which will be always same.

So, angle

- Now, angles BDM and CDM are complimentary angles, as shown in figure.
- Two angles whose adding gives are called as
**complimentary angles**.

So,

Now, , so **.**

So,

**Thus, angle**

## Question number: 136

### Write in Short

The diagram shows a regular pentagon and a square. Calculate the values of .

### Explanation

Here, pentagon is regular.

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

In pentagon number of sides = 5, so **exterior angle** =

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

Now, for angle :

As shown in figure, total angle is , so

.