AB |
AC |
8 |
3 |
∴|
AB |
AC |
8 |
3 |
1 |
2 |
AB |
AC |
∴cosA=
4 |
3 |
∴cosA=
4 |
5 |
3 |
5 |
∴sin2
B+C |
2 |
1-cos(B+C) |
2 |
1+cosA |
2 |
59 |
50 |
(2)∵sinA=
3 |
5 |
由S△ABC=
1 |
2 |
1 |
2 |
3 |
5 |
∴a2=b2+c2-2bccosA=4+25-2×2×5×
4 |
5 |
∴a=
13 |
AB |
AC |
8 |
3 |
B+C |
2 |
AB |
AC |
8 |
3 |
AB |
AC |
8 |
3 |
1 |
2 |
AB |
AC |
4 |
3 |
4 |
5 |
3 |
5 |
B+C |
2 |
1-cos(B+C) |
2 |
1+cosA |
2 |
59 |
50 |
3 |
5 |
1 |
2 |
1 |
2 |
3 |
5 |
4 |
5 |
13 |