Finding Area of Triangle

Area of a Triangle

Multiple Choice

Find the area of this square

• 5 cm

• 20 cm²

• 25 cm²

• 55 cm

Multiple Choice

Find the area of this square

• 10

• 10 square units

• 40 units

• 100 square units

Multiple Choice

When calculating the area of a square, you only need to know the measurement of 1 side because they are all the same.

• True

• False

Multiple Choice

What is the formula for the area of a rectangle?

• Length x Width

• Length x Length

• Width x Width

Multiple Choice

What is the formula for the area of a square?

• Length x Width

• Length x Length

• Width x Width

Multiple Choice

What is the area?

• 16 yd²

• 22 yd²

• 49 yd²

• 28 yd²

Multiple Choice

Find the area of the rectangle.

• 21 ft²

• 180 ft²

• 42 ft²

• 90 ft²

Multiple Choice

Find the area of the rectangle.

• 36 in.²

• 72 in.²

• 26 in.²

• 13 in.²

To use knowledge of the area of a rectangle to calculate the area of a triangle. 

To use knowledge of the area of a rectangle to calculate the area of a triangle. 

...wait, so knowing the area of a rectangle is going to help me know the area of a triangle? Ahhh, okay.

• A triangle is half as big as the rectangle that surrounds it

• Which is why the area of a triangle is one-half base times height.

• Area = 1/2 base x height

• https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-geometry-topic/cc-6th-area-triangle/a/area-of-triangle

So when looking at this triangle, we need some information to help calculate the area.

We'll need the base and height of the triangle.

Here we go, here's some information.

Can you spot the base and the height values?

Multiple Choice

To calculate the area of the triangle, we will use the number sentence: (remember the 1/2bh operation we must use)

• 1/2 x 8 x 7

• 1/2 x 7 x 8

• 1/2 x 6 x 6

• 1/2 x 7 x 6

Of course, to calculate the area of a triangle we will use 1/2bh - (1/2 x base x height)

Can you calculate the area?

Multiple Choice

Can you calculate the area of the triangle?

• 28cm²

• 56cm²

Multiple Choice

Find the area of the triangle.

• 96 in²

• 48 in²

• 20 in²

Multiple Choice

Find the area of the triangle.

• 10 cm²

• 24 cm²

• 12 cm²

Open Ended

Mo says the area of this triangle is 15cm² Is Mo correct?

If not, explain his mistake.

(You can click on the picture to make it bigger)

Open Ended

Apologies for sneezing over this beautiful right angled triangle! Is it possible to estimate the area of this triangle from the information you have?

(You can click on the picture to make it bigger)

Multiple Choice

Using the previous explanations, what would be the area of this triangle?

• 9

• 18

• 27