Question

in an isosceles triangle the base is 11 less than 3 times the length of the leg if the perimeter is 39 centimeters then find the length of the base
A. 14
B.10
C.19
D.20

Answer 1

suppose the legs are x meters each, the base is 3x-11
the perimenter: x+x+(3x-11)=39
5x=50
x=10
so the base is 3*10-11=19
the answer is C.

Answer 2

Answer:

Option C  $19\ cm$

Step-by-step explanation:

we know that

An isosceles triangle has two equal sides and two equal angles

Let

x------> the length of one equal side

y-----> the length of the base

The perimeter is equal to

$P=2x+y$

we have

$P=39\ cm$

so

$39=2x+y$ -------> equation A

$y=3x-11$ ------> equation B

substitute equation B in equation A

$39=2x+(3x-11)$

solve for y

$50=5x$

$x=10\ cm$

Find the value of y

$y=3(10)-11=19\ cm$