In 2004200520062007, the number that cannot be expressed as the square difference of two integers is?
two thousand and six
x²-y²=2006
(x+y)(x-y)=1003×2
x+y=1003
X-Y = 2, the equations have no integer solution
x+y=2
X-Y = 1003, the equations have no integer solution
It is known that the three sides of a triangle are three continuous non-zero natural numbers, and the triangle is an obtuse angle triangle
Let these three sides be n, N + 1, N + 2. Let a be the angle that the obtuse angle is n + 2
From cosine theorem
n^2+(n+1)^-2n(n+1)cosA=(n+2)^
2n(n+1)cosA=n^2-2n-3
Because a is an obtuse angle, so cosa
In a right triangle, if the hypotenuse is four times the height of the hypotenuse, the degrees of the two acute angles are ()
A.30°,60° B.15°,75° C.20°,70° D.25°,65°
Let the hypotenuse be 4, the height be 1, and the adjacent edge be √ 15
Then sine theorem: 1 / SiNx = 4 / sin90, find X
x=14.xxx
B is the closest. Choose B