It is 1,998 bigger than 2.
We know that
applying the law of cosines
a² = b²+ c²<span> – 2*b*c*cos(A)
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in this problem
a=?
b=20
c=9
A=90°
so
a² = b²+ c² – 2*b*c*cos(A)
but
cos (A)=0
a² = b²+ c²-----> 20²+9²----> a²=400+81----> a²=481-----> a=√481
a=21.93-----> a=22
the answer is
22
42 boxes of nails at .4 pounds a box would weigh 16.8 pounds.
