You had the right idea using the Pythagorean theorem to solve for b.
Problem is for that triangle to work, the 5 and the 2√2 would have to switch places. The length of a leg cannot be larger than the length of the hypotenuse for it to truly be a right triangle.
Pythagorean theorem only works for the right triangles. Only way to "solve this problem would be to bring in complex numbers.
5² + b² = (2√2)²
25 + b² = 2²(√2)²
25 + b² = 4(2)
25 + b² = 8
b² = 8 - 25
b² = - 17
b = √-17
b= (√17i)
Then the problem with THIS is a measurement/distance cannot be negative... which goes against exactly what that complex number i is.
40 is the answer for the equation 20+20=40
Length=2x
width=x
Perimeter of a rectangle=2(length) + 2(width)
We can suggest this equation:
24=2(2x)+2x
24=4x+2x
24=6x
x=24/6
x=4
length=2x=2(4)=8
width=x=4
area of a rectangle=length x width
area of this poster (rectangle)=(8 in)( 4 in)=32 in².
The area of this poster will be: 32 in²