A1 3)
sin^2 =1-cos^2 = 1- (-7/25)^2 =(625-49)/625
sin=24/25
A2 3)
cos^2 = 1- sin^2 = 1-(-5/13)^2 = (169-25)/169=144/169
cos= 12/13
tg = sin/cos= -5/13 /12/13 = -5/12
A3 4)
sin^2 = 1-cos^2 = 1-(3/5)^2=1-9/25=16/25
sin = -4/5
(1+tg )/(1+ctg) =1+tg /(1+1/tg) =1+tg /((tg+1)/tg)=tg = sin/cos= (-4/5)/(3/5)=-4/3
A4 3)
(1-sin)(1+sin)-(cos^2 - 5)=(1-sin^2)-(cos^2 - 5)=cos^2-cos^2 + 5= 5