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Which of the following could be an area of an isosceles triangle if the perimeter is 18 and one side is 8?
a) 6
b) 12
c) 14
d) 16
e) 18
OK, sounds easy enough. Perimeter = a + b+ 8 = 18 thus other two sides must equal 10 as its an isosceles.
8+2 =
5+5 =
Should be the only ones that work to give two equal sides (isosceles). But none work.
This book is crap!
The two equal sides are 5 units each... the base is 8 units... thus the height is 3 units... hence the area is 0.5*(base)*height = 0.5*8*3 = 12 sq. units.