Question

The edges of a triangular board are 3 m, 4 m and

5 m. If the cost of painting it is ` 10 per m2
, then

find the total cost of painting at only one face.​

Answer 1

Answer:

sides of triangle = 3m, 4m and 5m

perimeter = 3 + 4 + 5 = 12m

s = perimeter/2 = 12/2 = 6

area of triangle only using sides =

√s(s-a)(s-b)(s-c) = √6(6-3)(6-4)(6-5) = √6*3*2*1

= √36 = 6 sq. m

Rate of painting = 10/sq. m

Cost of painting = 10*6 = $60

Answer 2

Due to the three sides of the triangle we can say it is a right-angled triangle!
So
Base= 3m
Height=4m

.: Ar(Triangle) = 1/2 x b x h
=> 1/2 x 3 x 4
=> 1 x 3 x 2
=> 6m sq.

Total Cost of Painting = 6m sq x 10
=> ₹60