Are the points (2,3), (8, 11) and (-1,-1) form a triangle ? Explain.
If (9
and
Answers
Answer:
Solution:
External dimensions of book self,
Length, l = 85cm
Breadth, b = 25 cm
Height, h = 110 cm
External surface area of shelf while leaving out the front face of the shelf
= lh+2(lb+bh)
= [85×110+2(85×25+25×110)] = (9350+9750) = 19100
External surface area of shelf is 19100 cm2
Area of front face = [85×110-75×100+2(75×5)] = 1850+750
So, area is 2600 cm2
Area to be polished = (19100+2600) cm2 = 21700 cm2.
Cost of polishing 1 cm2 area = Rs 0.20
Cost of polishing 21700 cm2 area Rs. (21700×0.20) = Rs 4340
Dimensions of row of the book shelf
Length(l) = 75 cm
Breadth (b) = 20 cm and
Height(h) = 30 cm
Area to be painted in one row= 2(l+h)b+lh = [2(75+30)× 20+75×30] = (4200+2250) = 6450
So, area is 6450 cm2.
Area to be painted in 3 rows = (3×6450)cm2 = 19350 cm2.
Cost of painting 1 cm2 area = Rs. 0.10
Cost of painting 19350 cm2 area = Rs (19350 x 0.1) = Rs 1935
Total expense required for polishing and painting = Rs. (4340+1935) = Rs. 6275
Answer: The cost for polishing and painting the surface of the book shelf is Rs. 6275.