if mzbdc = 20, m arc ab = 140, and marc cd = 120, find m21.

Step-by-step explanation:

Given:

m ∠BDC = 20

m arc AB = 140

m arc CD = 120

Now, let the center of the circle be at point 'O'.

From the triangle AOB,

OA = OB (Radius of the circle)

∴ m∠ABO = m∠BAO = m ∠1

∵ m arc AB = 140

∴ m ∠AOB = 140 (Arc measure equals the angle subtended by the arc at the center)

Now, sum of all angles of a triangle is equal to 180. So,

Therefore, the measure of angle 1 is 20. So, the last option is correct.

i can answer this question sweetie!

step-by-step explanation: