Question

If the altitude of a triangle is increased by 40% and the base is decreased by 15% then find the % change in its
area
Select one:
a. 21% decrease
b. 21% increase
c. 19% decrease
d. 19% increase​

Answer 1

Answer:

let the altitude of 1st ∆ be h and base be b

then altitude of the ∆ after modification is 1.4 h and it's base is 0.85 b

area of ∆ without charges is A = 1/2bh

area of ∆ after modification is A'= 1/2* 1.4h * 0.85b

= 1/2 * 1.19bh

change in area = (1/2*1.19bh - 1/2bh)

= 1/2bh*0.19 = 0.19 A

% change = (0.19 A * 100)/A = 19% increase