Respuesta :

Since the line from top angle creates a right angle at the perpendicular, you can do the Pythagorean Theorem to get the length of the line on either side of it, then add the two numbers together.
a²+b²= c²
12²+b²= 13²
144+b²= 169
b²= 25
b= 5
a²+b²= c²
12²+b²= 20²
144+b²= 400
b²= 256
b= 16
16+5= 21feet

The length of ab in the given figure is 21 feet.

The following information should be considered:

  • As the line from the top angle develops the right angle at the perpendicular, so here we apply the Pythagorean Theorem.
  • This is applied so that the length should be measured on either side and then we added the two numbers together.

Based on the above information, the calculation is as follows:

[tex]a^2+b^2= c^2\\\\12^2+b^2= 13^2\\\\144+b^2= 169\\\\b^2= 25\\\\b= 5[/tex]

And,  

[tex]a^2+b^2= c^2\\\\12^2+b^2= 20^2\\\\144+b^2= 400\\\\b^2= 256\\\\b= 16[/tex]

Therefore, the length should be

= 16 + 5

= 21 feet

Learn more: brainly.com/question/22059747