4. A children’s play area is triangular. The sides of the play area measure 100m, 250m and 275m respectively. Calculate the area of the play area.
as before, use Heron's formula, or, if the sides in order are a,b,c then to find angle A, use the law of cosines (a^2 = b^2+c^2-2bc cosA)
100^2 = 250^2 + 275^2 - 2*250*275 cosA
and then the area is 1/2 bc sinA