The distance between city A and city B is 22 miles. The distance between city B and city C is 54 miles. The distance between city A and city C is 51 miles.
A
an acute triangle, because 222 + 542 >512B
an acute triangle, because 222 + 512 >542C
an obtuse triangle, because 222 + 542 >512D
an obtuse triangle, because 222 + 512 >542