The Answer is:
(5a2-3a+8)+(-4a2-1)+(15a+11)
2504, as 2499 is 5 less, yet rounds to 2.5K. It is the highest possible for rounding to the tens, as 2505 rounds to 2510.
I think I know what you're asking but I'm not 100% but there would be no equal sides or equal angles. Hope this helps!
It should be 18.84. To find the circumference of a circle you would times the diameter by pi or 3.14 but since its the radius you would need to times pi (by the radius and times that by 2. so 3 times 2 is 6 and 6 times 3.14 is 18.84