A triangle has side lengths of
a,
b, and
c centimeters. Does each angle in the triangle measure less than 90 degrees?
A triangle is acute if the square of the longest side is less than the sum of the squares of two smaller sides.(1) The 3 semicircles whose diameters are the sides of the triangle have areas that are equal to 3 \(cm^2\), 4 \(cm^2\), and 6 \(cm^2\), respectively.
Area of the semicircle with a cm as diameter \(= \pi a^2/8 = 3\)
Area of the semicircle with b cm as diameter \(= \pi b^2/8 = 4\)
Area of the semicircle with c cm as diameter \(= \pi c^2/8 = 6\)
Square of the longest side =\( c^2 = 48/\pi < a^2 + b^2 = 24/pi + 32/pi = 56\pi\)
The triangle is acute, i.e.each angle in the triangle measure less than 90 degrees
SUFFICIENT
(2) c < a + b < c + 2
a+b > c is always true
a+b<c+2
Case 1: a=2; b=3; c= 4; a^2 + b^2 = 2^2 + 3^2 = 13 < c^2 = 16; Triangle is NOT acute
Case 2: a=1; b=2; c=2; a^2 + b^2 = 1^2 + 2^2 = 5 > c^2 = 4; Triangle is acute.
NOT SUFFICIENT
IMO A