ちから平行 へいこう四辺 しへん けいだったら
chikarano heikō shi henkeidattara

Noun
Da Copula

The "-tara" conditional form ("if/when…") of 力の平行四辺形

1. If/when it were a parallelogram of forces:; If/when it's a force parallelogram:

Tara Conditional
Mathematics