Answer:
The length of the diagonal of a poster board is 
Step-by-step explanation:
Let
x----> the length of the diagonal of a poster board
we know that
Applying the Pythagoras Theorem

Equilateral triangle have the same side lengths. Perimeter = sum of all sides
(4x - 3) + (4x - 3) + (4x - 3) = 63
Remove parentheses
4x - 3 + 4x - 3 + 4x - 3 = 63
Combine like terms
12x - 9 = 63
12x = 72, x = 6
Solution: x = 6
Let
C---------> <span>the cost of a pizza
</span>t----------> <span>number of toppings
we know that
</span>$15.74-3t=$14.49-2t
15.74-14.49=3t-2t-------------> t=1.25
the cost of one topping is $1.25
and the cost of one pizza <span>without topping is
</span>15.74-3*1.25--------> $11.99
then
<span>an equation for the cost of a pizza, C, as a function of the number of toppings, t ordered is
</span>C=11.99+1.25t
the answer is
C=11.99+1.25t
x = length of one side.
1,232in^2 = x^2
Take the sqrt of both sides.
35.1 in = x
The length of one side = 35.1 in