Answer: Yes, the 3 foot 3 foot square opening in your ceiling is big enough to insert a 4x8 piece of plywood.
In a 3x3 foot square, we can form two right triangles with same diagonal side or hypotenuse. .
Using the Pythagorean theorem/formula, we can find the length of the hypotenuse or the longest side of the triangle ( c) given the two sides a and b
Substitute values a=3 and b=3 to formula
a^2^+b^2^=C^2^=
3^2^+3^2^=C^2^=
9+9= C^2^
C= square root of 18
C=4.24
A 4x8 piece of plywood can be inserted in a 4.24 opening diagonally.
