geometry
posted by lisa on .
an isosceles triangle has a perimeter of in. the congruent sides measure (2x+9)cm. The length of the third side is 3 x cm. what is the value of x?

What is the perimeter?

an isosceles triangle has a perimeter of 60 in. the congruent sides measure (2x+9)cm. The length of the third side is 3x cm. what is the value of x?
Again...sorry. = ) 
How do you think you should solve this problem?

I really have no idea. I am more confused with every question.

Are you sure that the perimeter is 60 inches?
2(2x + 9) + 3x = 60
Solve for x. 
If the perimeter is 90 inches, forget the solution I posted above.

19.2 cm?

x = 19.2cm? (the perimeterr is 60 in.)

Substitute 19.2 for x and see if it works.

It does...right? Oh Lord...

I'll bet the perimeter is 60 cm.
2(2x + 9) + 3x = 60
2(38.4 + 9) + 3(19.2) = 60
94.8 + 57.6 does not equal 60
Work this equation.
2(2x + 9) + 3x = 60
You should find that x is a whole number between 5 and 10. 
how about x=6...that works.

Yay! You got it!

really..cuz that answer I didn't convert cm to inches. when I do I get x = 18.86 now. Please confirm. my brain hurts.

Are you absolutely sure that the perimeter was given in inches, not centimeters?
If you are  then I'm off base because I've figured the perimeter as 60 centimeters. 
no, the perimeter is 60 inches. ha..hence the confusion.
1 in = 2.54 cm
60 in =152.4cm
7x=152.418
7x=134.4 / 7
x=19.2cm
Whadda ya think? 
Ahh! It looks like you're right.