A square playing field has an area of 1,255 square yards. About how long is each side of the field?

What is the missing step in this proof ?

45% of the trees in a park are apple trees. there are 27 apple trees in the park. how many trees are in the park in all?

Non-euclidean geometry was discovered when, in seeking cleaner alternatives to the fifth postulate, it was found that the negation could also be true a. true b. false