I need help, I am confused.

Refer to interactive solution 17.45 to review a method by which this problem can be solved. the fundamental frequencies of two air columns are the same. column a is open at both ends, while column b is open at only one end. the length of column a is 0.504 m. what is the length of column b?

What is sin 7x/4 ? i need on this urgent trig

Evaluate cos2θ for cosθ = square root of 3/2