a)
b² = 13² - 5²
b² = 169 - 25
b² = 144
b = 12
sinα = 12/13
cosα = 5/13
tgα = 12/5 = 2,4
ctgα = 5/12
b)
b² = 25² - 7²
b² = 625 - 49
b² = 576
b = 24
sinα = 7/25
cosα = 24/25
tgα = 7/24
ctgα = 24/7
c)
c² = 4² + 8²
c² = 16 + 64
c² = 80
c = √80 = 4√5
sinα = 8/4√5 = 8√5/20 = 2√5/5
cosα = 4/4√5 = 4√5/20 = √5/5
tgα = 8/4 = 2
ctgα = 4/8 = 1/2
