Answer:
d. none of the above
Step-by-step explanation:
it's this because if Yu really think Abt it none of these if formula
A decagon is a polygon which has ten sides. A regular decagon is characterized by equal side lengths. An important dimension of this polygon is the side length. The area is expressed as:
A=(5/2)a^2(√5+(2√5))
A = <span>(5/2)16^2(√5+(2√5))</span>A = 1969.72
In this question, we use law of cosine which is

Substituting the given values of RS,RT, ST , we will get


Taking inverse cosine on both sides


|PR| = |PQ| + |QR|; |PQ| = |QR| conclusion |PR| = 2|PQ|
|PQ| = 3y; |PR| = 42; |QR|=?
subtitute
42 = 2(3y)
6y = 42 |divide both sides by 6
y = 7
|QR| = 3(7) = 21