Question

解三角形公式 sin几度怎么求,比如 b=26cm c=15cm C=23度,用余弦定理求的话,cos23度怎么化成正常

Answer 1

a^2=b^2+c^2-2*b*c*Cos(A)

=26^2+15^2-2*26*15*Cos(23°)

=183

a=sqr(183)=13.5278

b/Sin(B)=c/Sin(C)=a/Sin(A)

A=arcsin(a/c*Sin(C))

=20.6°或159.37°

拿计算器按,没法手算.两个答案,