单选题If the radius of a circle is increased by 40%, how much will the area increase?A16%B20%C40%D80%E96%
单选题
If the radius of a circle is increased by 40%, how much will the area increase?
A
16%
B
20%
C
40%
D
80%
E
96%
参考解析
解析：
设圆的半径为r，故面积S=πr2，若半径增加40%，那么面积S’=π(1.4r)2=1.96πr2，故半径增加了96%，本题选择E项。
设圆的半径为r，故面积S=πr2，若半径增加40%，那么面积S’=π(1.4r)2=1.96πr2，故半径增加了96%，本题选择E项。
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