Y+4x=0
y=-4x
вот график сфоткал
Sin²t=1:(1+ctg²t)=1:(1+441/400)=1:841/400=400/841
sint=20/29
cost=-√(1-sin²t)=-√(1-400/841)=-√(441/841)=-21/29
tgt=sint/cost=20/29;(-21/29)=-20/29*29/21=-20/21
или tgt=1/ctgt=1:(-21/20)=-20/21
аn = a1 + (n - 1)d
a17 = - 15 + (17 - 1) * 3 = - 15 + 16 * 3 = - 15 + 48 = 33