1. the surface area of a red-hot steel bar decreases by 5% when it completely cools down.Find the percentage change in its length.
2.The picture shows a small print of a Persian cat.A larger print of the picture is36cm inheight.If the two prints are similar measure the size of the small print and then find the perimeter and area of the larger print. (The smaller pictureis 4CM X 3CM)
plz show the steps~
點解咁計?
f.3體績問
2006-12-31 5:41 am
回答 (1)
2006-12-31 7:47 am
✔ 最佳答案
1. Since (the percentage change on area) = (the percentage change in length)²therefore : (1-5%) = (the percentage change in length)²
the percentage change in length = √0.95 = 0.975
2. Let w be the width of the larger print
Since the two prints are similar measure in size:
36/4 = w/3
w = 27
The perimeter of the larger print : (36+27) x 2 = 106 cm
The area of the larger print : 36 x 27 = 972 cm²
收錄日期: 2021-04-18 20:31:13
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