GCSE Maths Intermediate Interior/Exterior angelsWatch

This discussion is closed.
#1
Hi,

I am doing a question on interior/exterior angels i can solve it but only via trial and error.

"Find the value of X in the following Polygon" Interior angels shown as 2x, x+20, 2x+5, 85.

Answer= x=50. 180-100=80; 180-70=110; 180-105= 75, 180-85=95

80+110+75+95=360 (exterior angles sum). Therefore x 50 is correct, as stated though this answer was only obtained via trial and error.

Is there a easier way then trial or error or is this the required method for intermediate level?

Thanks
5by5
0
13 years ago
#2
2x + x+20 + 2x+5 + 85 = 360 (interior angles add up to 360)

5x + 110 = 360 (simplify)

5x = 250 (-110 from both sides)

x= 50
0
#3
(Original post by Speleo)
2x + x+20 + 2x+5 + 85 = 360 (interior angles add up to 360)

5x + 110 = 360 (simplify)

5x = 250 (-110 from both sides)

x= 50
Thanks for that.
0
13 years ago
#4
No problem
You can pm me if you're stuck on any more GCSE questions if you like.
0
13 years ago
#5
Have a look at the revision notes at www.mathsangel.co.uk - they're free I think.
0
X
new posts
Latest
My Feed

Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

University open days

• University of East London
Wed, 23 Jan '19
• University of East Anglia
All Departments Open 13:00-17:00. Find out more about our diverse range of subject areas and career progression in the Arts & Humanities, Social Sciences, Medicine & Health Sciences, and the Sciences. Postgraduate
Wed, 30 Jan '19
• Aston University
Wed, 30 Jan '19

Poll

Join the discussion

Remain (1439)
79.72%
Leave (366)
20.28%