What is 9.8846387057 to the nearest whole number

Which triangle congruence postulate or theorem justifies my claim that the steps i made using construction paper and scissors produce an isosceles triangle? was it sss, sas, asa, aas, or hl?

Graph the following system of linear inequalities. identify at least two points in the solution: y < 5 - 2x | x + 5y > -7

Me with these questions , i don’t understand scientific notation!