Question

Work out the value of A

Answer 1

Answer:

that is really so difficult ? what do you not understand here ? please let me know, if you need any further explanations.

you know what the perimeter is ? if it's the circumference, the way around the object. in other words, the distance you have to walk, when going along all sidelines of the object.

so the perimeter is the sum of of all side lengths.

56 = x - 1 + 3x + 3x + 1 = 7x

x = 8

that gives us the side lengths :

x - 1 = 7 cm

3x = 21 cm

3x + 1 = 22 cm

the formula for the area of a triangle

A = baseline × height / 2

the advantage of a right-angled triangle in this regard is that the sides enclosing the 90 degree angle are already "acting" as baseline and the height (standing on the baseline with a 90 degree angle).

so, we can simply say here, the 3x side is the baseline, and the x-1 side is also the height.

therefore,

A = 21×7/2 = 147/2 = 73.5 cm²