Question

If ARC CD = 143°, and ARC AB = 39°, what is m∠DEC?

https://media.glynlyon.com/g_geo_2012/13/img_geou13a_54.gif

88°
89°
90°
91°

Answer 1

m∠DEC = (ARC DC + ARC AB) / 2
now I think you can find the answer...

Answer 2

@PFEH.1999 then do you think you could help me out with this question too??

If ARC AC = 80°, and m∠BED = 25°, what is ARC BC ?

https://media.glynlyon.com/g_geo_2012/13/img_geou13a_56.gif

55°
30°
65°
20°

Answer 3

Yes!
m∠BED = (ARC AC - ARC BD) /2

Answer 4

so would the equation be 80 - 25 over 2??

Answer 5

m∠BED = 25
ARC AC = 80
so:
25 = (80 - ARC BD) / 2 --> 80 - ARC BD = 25x2 --> 80 - ARC BD = 50
--> 80 - 50 = ARC BD --> ARC BD = 30

Answer 6

@ttop0816 , Did you get it?