tgα=sinα/cosα
sin²α+cos²α=1 , cos²α=1-sin²α=1-36/61=61/61-36/61=25/61, α∈(0,π/2)
cosα=√(25/61)=5/√61
tgα=(6/√61)/(5/√61)=6/5
tgα=sinα/cosα
sin²α+cos²α=1 , cos²α=1-sin²α=1-36/61=61/61-36/61=25/61, α∈(0,π/2)
cosα=√(25/61)=5/√61
tgα=(6/√61)/(5/√61)=6/5