The triangle is an obtuse triangle. No sides are equal.
convert cm to dm
1 dm = 10 cm
side a: 20 cm ⇒ 20cm * 1dm/10cm = 20dm/10 = 2 dm
side b: 30 cm ⇒ 30cm * 1dm/10cm = 30dm/10 = 3 dm
side c: 40 cm ⇒ 40cm * 1dm/10cm = 40dm/10 = 4 dm
We need to get the area of a triangle, but first we need to solve for its height using Heron's formula
s = (a+b+c)/2 = (2+3+4)/2 = 9/2 = 4.5
Area = √(s(s-a)(s-b)(s-c)
h3/2 = √4.5(4.5-2)(4.5-3)(4.5-4)
h3/2 = √4.5(2.5)(1.5)(0.5)
h3/2 = √8.44
h3/2 = 2.91
h = (2.91*2)/3
h = 1.94
A = hb/2 = (1.94*3)/2 = 5.82/2 = 2.91 dm²
48 dm² / 2.91dm² = 16.5 or 17 tiles needed
17 x Rs200 = Rs3,400 is the total cost