Mathematics
Grade9
Easy
Question
The height (but not the base) of a triangle is doubled. Describe the effect on the area.
- The area is doubled
- The area is quadrupled
- The area is halved
- The area is tripled
Hint:
We are given that the height of a triangle is doubled and the base of the triangle is kept constant. We have to find the change in area.
The correct answer is: The area is doubled
The formula for area of triangle is 1/2 × b × h
Here, base is constant
Height of the triangle is doubled.
Let A1 be the area original triangle.
A1 = 1/2 × b × h
Let A2 be the area of changed triangle.
A2 = 1/2 × b × h
= 1/2 × b × 2h
= bh
Now we will take the ratio of changed area to original area.
Ratio = A2/A1
= 2
So, the area of the triangle is also doubled.
For such questions, we should know area of different shapes.
