Resolution oscillation frequency

Hello everyone !

I'm new Mathcad user and do not have much practice with the tool. I would like to help.

Can anyone help me solve this problem with Mathcad?

To determine the frequency of oscillation of the pendulum harmonic figure next to

Data :

m = 5 Kg

K1 = 50 N/m

K2 = 130 N/m

mR = 10 kg

R = 1,2 m

Applying the solution by the energy equation method

Simply:

Deriving and operating:

Replacing variables:

Simply:

The expression of the natural frequency is thus:

Thanks!