Answer:
First, we must know the formula for the area of a triangle.
A = BH x 1/2
Where 'b' represents the base, and 'h' represents the height.
Multiplying by 1/2 basically means dividing the result of (base x height) by 2.
Now we plug in what we know, given the dimensions shown.
We know that the area is 90 square units.
We also know that the height is 9, so;
A = BH x 1/2
90 = B(9) x 1/2
Solve for B:-
90 = 9b(we reverse b9 because they both serve as the same thing) x 1/2
90 = 9b x 1/2
Dividing by 1/2 also means multiplying by 2, so we multiply 2 to both sides to get rid of 1/2;
*2 *2
180 = 9b
To isolate b(base) we divide by 9 from both sides because the inverse operation of multiplication is division.
÷ 9 ÷ 9
20 = b, our base is 20 square units.
