номер 718-720 пжпжпж

718. AB^2=7^2+24^2=25; AB=5

sin B=7/25; cos B=24/25

719. tg B=AC/BC; AC=a*tg B

cos a= AC/AB; AB= b/cos a

720. tg a=BC/AC; BC=b*tga

sin b=BC/AB; AB=a/sin b