Question

In circle A shown below, BD is a diameter and the measure of CB is 36°. What is the measure of ∡DBC?

36°

72°

18°

54°

Answer 1

@jim_thompson5910 can you look at this? I got the answer 54..

Answer 2

A is the center. So DAB is 180 degrees since "BD is a diameter"

Therefore, arc DBC is 36+180 = 216

which leaves 360 - 216 = 144 for arc DC

Are you seeing how I'm getting all this?

Answer 3

ohhhh okay. I did DCB=90
angle BDC=36 degrees
so angle DBC=180-(angle BDC+ angle DCB)=180-(36+90)=54 degrees

Answer 4

ah, that's where you made a typo...

angle BDC is NOT 36 degrees

Answer 5

the central angle BAC is 36 degrees, and using the inscribed angle theorem, BDC is what?

Answer 6

Ohhhh, I see what i did!!

Answer 7

that's great

Answer 8

so what is the final answer then?

Answer 9

36

Answer 10

close...but not quite

Answer 11

would it be 18?

Answer 12

no

Answer 13

You should have gotten that angle BDC is 18 degrees, so


angle DBC=180-(angle BDC+ angle DCB)=180-(18+90)=72 degrees

Answer 14

Alright...thank you

Answer 15

you're welcome