1.cosB=4/5=0,8- C)
2.sinA=√(1-25/89=√64/89==8/√89, tgA=8/√89:5/√89=8/5=1,6-D
3.cosa=√1-15/16=√1/16=1/4=0,25 - A
4.sinA=√1-24/25=√1/25=1/5=0,2- B
5.1+tg²A=1/cos²A, 1+9·7/49=1+9/7=16/7, 1/cos²A=16/7,cos²A=7/16,cosA=√7/4,sinA=√1-7/16=√9/16=3/4,
cosB=sinA=3/4=0,75-F
6.COSa=√1-81/181=√100/181, tgA=9/√181:10/√181=9/10=0,9