# Measure of angle D

Printable View

• Jan 5th 2013, 06:59 PM
rcs
Measure of angle D
ABCD is inscribed in circle O. If angle B is 110 and angle C is 80. What is angle D?

whatt made me confuse here is that we know that consecutive angles of a quadrilateral are supplementary but 110 + 80 is 190. It impossible now to find angle D. Please guide me on this

thanks
• Jan 5th 2013, 07:07 PM
MarkFL
Re: Measure of angle D
What we know is that opposite angles of a cyclic quadrilateral are supplementary.
• Jan 5th 2013, 08:26 PM
ibdutt
Re: Measure of angle D
There is no such property as mentioned: consecutive angles of a quadrilateral are supplementary.
• Jan 6th 2013, 07:55 AM
Plato
Re: Measure of angle D
Quote:

Originally Posted by ibdutt
There is no such property as mentioned: consecutive angles of a quadrilateral are supplementary.

@ibdutt, I hope that you just over looked the term cyclic.
It is certainly true that opposite angles of a cyclic quadrilateral are supplementary.

What is not true is "consecutive angles of a quadrilateral are supplementary." That is the true of a parallelogram.
• Jan 6th 2013, 08:17 AM
ibdutt
Re: Measure of angle D
Thanks for your response. I stick to my response that "consecutive angles of a quadrilateral are supplementary" there can be no doubt that the opposite angles of a cyclic quadrilateral are supplementary..
• Jan 7th 2013, 06:30 AM
rcs
Re: Measure of angle D
i know now the answer and i got it... it is 70 degrees