a^2+b^2=(n^2-1)^2+(2n)^2
=n^4-2n^2+1+4n^2
=n^4+2n^2+1
=(n^2+1)^2
c^2=(n^2+1)^2
a^2+b^2=c^2
由勾股定理
所以是直角三角形
快点,一道数学选择题,急.快啊,明天就要交作业的.
a^2+b^2=(n^2-1)^2+(2n)^2
=n^4-2n^2+1+4n^2
=n^4+2n^2+1
=(n^2+1)^2
c^2=(n^2+1)^2
a^2+b^2=c^2
由勾股定理
所以是直角三角形