Odpowiedzi

2009-11-28T22:50:55+01:00
1.
tgα=1/3
a=1
b=3
c=?
a²+b²=c²
1²+3²=c²
1+9=c
c=√10
c=2√5
sinα=1/2√5
5(2sin²-1)
5(1/2√5-1)=5(2√5/10 - 1)=5(√5/5-1)=
=√5-1

2.
a=5
b=1
c=?
5²+1²=c²
c=√26

sinα=5/2√26=5√26/26
cos=1/2√26=√26/26

=5√26/26-(√26/26 * 26/5√26)+√26/26=5√26/26-1/5+√26/26=5-1/5=4 4/5