Will tension of a pendulum changes when it is oscillatin?why?

The tension of an osciallting pendukun is derived as :

  …...(1)

Here, theta is the angle made by pendulum with vertical line drawn through pivot. So at 90 degrees or the pendulum is horizonatl, the first term is zero, and when 0 degress or the pendulum is vertical, the first term is zero or in other words the tension is maxium. Between 0 and 90 degrees the tension changes and varies from max tension to minimum tension.

 

So at 90 degrees, the tension is,

 

Yes it changes.