Answer:
c and d
Step-by-step explanation:
i think
Yes.
To form a triangle every side must be smaller in length than the sum of the two other sides.
For example: sides denoted by a,b,c
for a triangle to form
a<b+c
b<a+c
c<a+b
Thus in the case of the <em>Isosceles </em>triangle with side lengths 1,8,8 the rules aforementioned are fulfilled. This means that a triangle with said side lengths can exist.
It would be 3.375 before rounding so if you round it to the nearest whole number it would be 3 since be hind the first 3 is under 5
A rectangular prism and a cylinder a rectangular prism and a cone a cylinder and a cone a cylinder and a pyramid
Step-by-step explanation:

The quadratic formula is honestly the most straightforward way of solving here.
Your other options are completing the square (which is the same thing as the quadratic formula but it's good to know that method if you have to take Integral Calculus at some point) or maybe factoring by grouping if it's appropriate. But the quadratic formula will work for you in all three equations:
1) a=1, b=0, c=8
This reduces pretty quickly into x=8i,-8i due to the negative under the radical. (Actually we didn't even really need the formula here.)
2) a=-9, b=4, c=-10
This reduces into x=(-4+i√(344))/-18, (-4-i√(344))/-18 and doesn't go any further because 344 isn't a perfect square.
3) a=1, b=8, c=17
This reduces to x=(-4+i), (-4-i)
So those are the answers for each.