9514 1404 393
Answer:
x = 30
Step-by-step explanation:
In an arithmetic sequence, any given term is the average of the two terms that come before and after. The middle term of this sequence must be ...
2sin(3x) = (-11 +15)/2
sin(3x) = 1 . . . . . . . . . . simplify and divide by 2
Then the value of 3x must be 90°, so ...
x = 90/3 = 30
There is one value of x in the interval [0, 90] that makes this sequence arithmetic: x = 30.
