Maths help please

[mrsglowglow]

If anyone could help my son I would appreciate it. He is only getting 1 mark out of 4 and has been trying for ages. Thanks x

[dementedpixie]

As the 2 angles are the same does that mean the 2 sides are equal? If so you can work out what x equals i.e.

3x-5 = 19-x
3x+x =19+5
4x = 24
X=6

So the equation you had for perimeter turns into
4×6 + 14 = perimeter
So P = 38

(Is thst correct somebody?)

[JustPurple]

He has the right idea!

The next step is for working out the value of x based on the fact that an isosceles triangle has 2 equal length sides (ie the left side - 3x - 5, is equal to the right side 19 -x)
From here you can substitute in the value of x to calculate the perimeter.

Another mark may be for including the units.

Do you need to see the working set out?

[mrsglowglow]

Thank you yes please!

[dementedpixie]

I just showed you!

[CoteDAzur]

Exactly as demented calculated.

OP - Does your OP not understand that two sides of an isosceles triangle are equal in length? He needs to start with:

3x - 5 = 19 - x

[CoteDAzur]

Does your DS not understand...

[mrsglowglow]

Thank you demented and all. He is still getting to grips and just starting these types of questions. He understood once i showed him your explanation but i think he needs to go back to the beginning with algebra. Thanks