The circle below has center C. Suppose angle EDF = 84º and DF is tangent to the circle at D. Find the following. Type your numerical answers (without units) in each blank.

=  168° and ∠ECD =  168°

Step-by-step explanation:

In the given , we have a circle centered at C , ED is a chord and DF is a tangent touching circle at D, ∠EDF = 84°.

Also, CE = CD = radius

⇒ ∠CED = ∠CDE  ---(i)  [angles opposite to equal sides of triangle are equal]

Since radius makes a right angle with tangent.

So, ∠CDF = 90°

⇒ ∠CDE =∠CDF - ∠EDF

⇒ ∠CDE=  90° - 84°

⇒ ∠CDE = 6°

From (i) ∠CED =∠CDE = 6°

In ΔCDE

⇒∠CED + ∠CDE + ∠ECD =  180°

⇒ 6°+6°+ ∠ECD =  180°

⇒ 12°+ ∠ECD =  180°

⇒∠ECD =  180° - 12°

⇒∠ECD =  168°

Since , Angle measure of the central angle is equal to the measure of the intercepted arc.

Therefore m∠ECD =

⇒=  168°

Hence,  =  168° and ∠ECD =  168°

answer:

c. the third graph