Question

use this rule to calculate the area of the following triangles and match to an answer in the middle. area = 1/2×4×3 = 6cm²

Explanation:

Step1: Recall area formula

The area formula for a triangle is $A=\frac{1}{2}\times base\times height$.

Step2: Calculate first triangle area

For the triangle with base $20$ cm and height $12$ cm, $A_1=\frac{1}{2}\times20\times12 = 120$ $cm^{2}$.

Step3: Calculate second triangle area

For the triangle with base $28$ cm and height $11$ cm, $A_2=\frac{1}{2}\times28\times11=154$ $cm^{2}$.

Step4: Calculate third triangle area

For the triangle with base $15$ cm and height $14$ cm, $A_3=\frac{1}{2}\times15\times14 = 105$ $cm^{2}$.

Step5: Calculate fourth triangle area

For the triangle with base $20$ cm and height $16$ cm, $A_4=\frac{1}{2}\times20\times16=160$ $cm^{2}$.

Step6: Calculate fifth triangle area

For the triangle with base $30$ cm and height $15$ cm, $A_5=\frac{1}{2}\times30\times15 = 225$ $cm^{2}$.

Step7: Calculate sixth triangle area

For the triangle with base $12$ cm and height $12$ cm, $A_6=\frac{1}{2}\times12\times12 = 72$ $cm^{2}$.

Step8: Calculate seventh triangle area

For the triangle with base $14$ cm and height $7$ cm, $A_7=\frac{1}{2}\times14\times7=49$ $cm^{2}$.

Step9: Calculate eighth triangle area

For the triangle with base $36$ cm and height $16$ cm, $A_8=\frac{1}{2}\times36\times16 = 288$ $cm^{2}$.

Answer:

First triangle: $120$ $cm^{2}$
Second triangle: $154$ $cm^{2}$
Third triangle: $105$ $cm^{2}$
Fourth triangle: $160$ $cm^{2}$
Fifth triangle: $225$ $cm^{2}$
Sixth triangle: $72$ $cm^{2}$
Seventh triangle: $49$ $cm^{2}$
Eighth triangle: $288$ $cm^{2}$