Answer:
We have to first see that the given lengths makes a triangle or not by using a+b > c in which a,b and c are
length of sides of a triangle lets check out
16 + 21 = 37 > 28
21 + 28 = 49 > 16
16+ 28 = 44 > 21
As because the statement fits correct in the lengths given so its a triangle
So we can say that the triangle is scalene by means of measurements
but cant be a right angle as by taking the pythagorean triplet
= a^2 + b ^ 2 = c^2
lets see if a=16, b = 21 and c = 28
So a^2 + b^2
= 256 + 441
= 697
but c^2
= 28^2 = 784
As 441 =/= 784
So The triangle lengths cant be a right angled triangle
So 1/2 of possibility is the traingle acute and 1/2 of the possibilty that the triangle is obtuse
Now you can find the correct triangle on the basis of acute or obtuse angle by drawing with given length of sides of triangle
Hope it helps