Answer:
Step-by-step explanation:
Area of outer triangle = [tex]\dfrac{4x*(4x+3)}{2}= 2x*(4x +3)[/tex]
= 2x*4x + 2x*3
= 8x² + 6x
Area of inner triangle= [tex]\dfrac{2x*(2x+5)}{2}=x*(2x+5)=x*2x+x*5=2x^{2} + 5x[/tex]
Area of aluminium = area of outer triangle - area of inner triangle
= 8x² + 6x + 2x² + 5x
= 10x² + 11x
Area of 20 aluminum borders = 20*(10x² + 11x) = 200x² + 220x
b) x = 25 cm
Area of 20 aluminum borders = 200*25² + 220*25
= 200 * 625 + 220*25
= 125000 + 5500
= 130500 cm²
c) Area of inner triangle (Glass) = 5500 cm²
Cost of aluminium = 130500 * 0.06 = $ 7830
Cost of glass = 5500 * 0.03 = $ 165
Cost of making 20 windows = 7830 + 165 = $ 7995
