Grade Six Mathematics

Answers to last week’s exercises:

1. An isosceles acute-angled triangle has two sides equal and all three angles measuring less than 90o.

2. An isosceles right-angled triangle has two sides equal and one angle measuring 90o.

3. An equilateral triangle is also called an equiangular triangle. 4. An equilateral triangle has all sides and angles equal.

5. An isosceles obtuse-angled triangle has two sides equal and one obtuse angle.

Hello Boys and Girls!

You should have noticed that:

-Equal sides of a triangle are opposite equal angles.

- The longest side of a triangle is opposite the largest angle.

- The shortest side of a triangle is opposite the smallest angle.

- The number of equal sides of a triangle equates to the number of equal angles.

Let us now look at the right-angled triangle

Right-angled triangles and the hypotenuse

A right-angled triangle consists of two legs and a hypotenuse. The two legs meet at a 90° angle and the hypotenuse is the side opposite the right angle.

Congruent Triangles

When two triangles are congruent they will have exactly the same three sides and exactly the same three angles. The equal sides and angles may not be in the same position (if there is a turn or a flip), but they are there.

Perimeter of Triangles

We will continue with Triangles this week.

Example 1: Find the perimeter of the triangle.

Example 2: Find the length of side x if the perimeter of the triangle is 28 cm.

Side = P – (s+s)

= 28cm – (13cm + 5cm) = 28cm – 18cm

= 10 cm

Let us now do some exercises based on this week’s and last week’s work.

Write in the missing quantity or name each of the following triangles as necessary.

Let us now take a peek at Area of Triangles

To find the area of a triangle, multiply the base by the height, and then divide by 2. The division by 2 comes from the fact that a parallelogram can be divided into 2 triangles. For example, in the diagram below, the area of each triangle is equal to one-half the area of the parallelogram.

Bye Boys and Girls. Until next week! SAFE!

Let the word FOCUS be your motto. BE

Conditions for the Congruence of Two Triangles The perimeter of any shape is the distance around it. Perimeter of Triangles = Side + Side + Side or S+S+S. Side = Perimeter – (Side + Side) or P – ( S+S).

Perimeter of triangle = (S+S+S) = 7cm + 12cm + 9cm = 28cm

Area of Triangle = (B X H)/2 = (14m X 10 m)/2 = (140 m)/2 = 70 m^2