Question

if the height of a triangle is decreased by 40% and its base is increased by 40%,what will be it area.Will it decrease or increase by how much percentage

Answer 1

let initial base=b, 
            height=h
area, A₁ = 0.5 bh

after height is decreased by 40% and base is increased by 40%,
base = 1.4b
height = 0.6h
Area, A₂ = 0.5×1.4b×0.6h = 0.42 bh

A₂ - A₁ = 0.42 bh - 0.5 bh = -0.08 bh
-ve sign indicates that area decreased.

% decrease = (0.08bh/0.5bh)×100 = 16%

Hope This Helps :)