20 tulips. 2/3=20/30 when you multiply both the denominator and numerator by 10.
No they don't.
Phythagorean triple is when the sum of the squares of two numbers is equal to the square of another number.
20^2 + 24^2 = 400 + 576 = 976
31^2 = 961
20^2 + 24^2 should have been equal to 31^2 but that's not the case. So, the side's length don't form a triple.
Hope it helped!
Reversing the clauses of an "if-then" statement only sometimes makes the new statement true, so it isn't true or false. For example, reversing the clauses of "if 1=x, then x=1" makes the new statement true, but reversing the clauses of "if x=2, then |x|=2" doesn't.

and surely you know how much that is.
To solve for the last side of the triangle, use the Pythagorean Theorem:
(8)^2 + x^2 = (9)^2
x = sqrt of 17
However, this is a NEGATIVE sqrt 17 because the terminal side is in quadrant 4, meaning that this side is under the X-axis and therefore negative.
Now that you know the side opposite of u in the triangle, do opposite/hypotenuse.
sin u = -(sqrt 17)/9