Answer:
40
Step-by-step explanation: A rectangle is a quadralaterial with 4 90 degree angles made up of two diagonals. If we draw one diagonal, it would split the rectangles into two right triangles. Since a rectangle has a right angle, we can use pythagorean theorem to solve the missing side.
[tex]a^{2} +b^{2} =c^{2}[/tex] where a and b are the length and widith and c is the diagonal length. Let plug it in
[tex]30^{2} +b^{2} =50^{2}[/tex]
900+[tex]b^{2}[/tex]=2500
[tex]b^{2} =1600[/tex]
[tex]\sqrt{1600 =[/tex]40
b=40
