Adjacent angles on a straight line/supplementary angles

stellina91 · 2008-04-15 15:37:39

What is the difference between adjacent angles on a straight line and supplementary angles.

Please look at the diagram below. E.g. If I wanted to find angle ADC do I say ADC = 180 - a + 60 (adj. angles on a st. line, or supplementary angles)

Thank you.

LuisRodg · 2008-04-15 16:17:28

If you want to find ADC you would say:

180 - (a + 60) = 180 - a - 60 = 120 - a

which is quite different from 180 - a + 60.

stellina91 · 2008-04-15 16:39:16

Thanks but what would my reason be? Adjacent angles on a straight line or supplementary angles?

Thanks.

LuisRodg · 2008-04-15 16:57:29

To be honest with you, I took geometry a long time ago. I found all the course to be mostly common sense but I forgot the names of the theorems.

Anyways, I did some googling and it is because of supplementary angles.

stellina91 · 2008-04-15 17:13:13

Thanks a lot!!!!!!

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