Look at the power triangle, kW kVA kVAR formula can be written as below,
kVA2 = kW2 + kVAR2

kVA = √ (kW2 + kVAR2)

Look at the above formula, the kVA is equal to the square root of the sum of the square of the kW and KVAR. //

kVAR is equal to the sin of power angle times of kVA.

kVAR = kVA * sin(φ)

or

Reactive power = apparent power * sin of power angle.
The power angle φ can be calculated by the cosine inverse of power factor //

kVAR is equal to the tan of kW. Hence the formula can be

kVAR = kW * tan (φ)

Reactive power in kilo volt-ampere reactive = kW * tan (power angle)