Answer:

Step-by-step explanation:
we know that
An exterior angle of a triangle is equal to the sum of the opposite interior angles.
see the attached figure to better understand the problem
so
∠DEF=∠ECD+∠CDE
substitute the given values

solve for x
Combine like terms

Group terms



Find the measure of angle CDE

substitute the value of x

Let

be the

th partial sum of a geometric sequence with common ratio

and first term

. So the sequence is

, and

is

Multiplying both sides by

gives

and subtracting

from

gives



If

, then

as

and so the sum approaches
Answer:if a=7, c=25 then the other one i don't know sorry
Step-by-step explanation:
If rad=3pi/2 then the angle is 3pi/2*180/pi