Starting from the fundamental trigonometric equation, we have

Since
, we know that the angle lies in the third quadrant, where both sine and cosine are negative. So, in this specific case, we have

Plugging the numbers, we have

Now, just recall that

to deduce

Answer:
∠ADB ≅ ∠CBD
Step-by-step explanation:
The three arcs at each of D and B identify congruent angles. However, the angles cannot be identified by their vertices alone. The 3-letter designations of the congruent angles are ...
∠ADB ≅ ∠CBD
Answer:
D
Step-by-step explanation:
Its D because A is all 90 degrees
Not C because all 90
Answer:
it is a 90 degree angle
Step-by-step explanation:
because the little square in the corner