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�b�P�� 10^o ��F��V�s�Y�W�A�]��] �Y�P��^�߰_�@�ںX��C ��q��H�� 60^o ��g�b�s�Y�W�ɡA�X�񪺼v�l�� 11 ��ءA�p�U�ϩҥܡ] �䤤�b�Y��ܶ��g��V�A�Ӳʶ½u�q��ܺX�񪺼v�l�^�C

$\begin{picture}(166,72) \thinlines\drawpath{12.0}{6.0}{154.0}{6.0} \drawpath{152... ... \drawcenteredtext{160.0}{6.0}{�F} \drawcenteredtext{6.0}{6.0}{��} \end{picture}$

�հݺX�񪺪��׳̱��H�U��@�ﶵ�H

(1) 19.1 �� (2) 19.8 �� (3) 20.7 �� (4) 21.1 �� (5) 21.7 ��

�ѦҼƭ�: sin 10^o $\thickapprox$ 0.174, sin 20^o $\thickapprox$ 0.342, cos 10^o $\thickapprox$ 0.985, cos 20^o $\thickapprox$ 0.940, $\sqrt{3}$ $\thickapprox$ 1.732

��:��D�O�@�Ӱ򥻪��T��D, �u�n��D�n��Q��@�ӤT��, �B�ξA��T��ʽ�(�p��w�z)�N��B�z.

��K�_��ڭ̥O�X�� A, �X��v�l��I�]�� B, �ӺX��I�]�� C. �ѩ��D�ؤw��X�񪺼v�l��, �ӰݺX�񪺪��, �ܦ۵M��ڭ̴N�O�n��Q $\vartriangle$ ABC. �ڭ̪u�Τ@��ߺD��Ÿ��]�w, �� A, B, C ��ܤT�� ABC �T�Ӥ��, �Ӥ��O�� a, b, c �� A, B, C �� (�Y $\overline{BC}$ , $\overline{CA}$ , $\overline{AB}$ ) ��, �p�U�ϩҥ�.

$\begin{picture}(166,72)(0,6) \thinlines % drawpath\{12.0\}\{6.0\}\{154.0\}\{6.0\... ...t{130.0}{16.0}{\small$B$} \drawcenteredtext{84.0}{74.0}{\small$C$} \end{picture}$

��U�ӧڭ̱N $\vartriangle$ ABC �Ҫ��T��C�X, ��D�N�� c = 11, �� A = 90^o - 10^o = 80^o �B C = 90^o - 60^o = 30^o, �̦��ڭ̥i�o B = 180^o - (A + C) = 70^o. �D�شN�O�n�ڭ̨̳o�ǰT��D�X b ��. �o�i�Ϋܦh��k�B�z, �o�̧ڭ̷Q�Q�Υ��䨤��Y�T�{�@�ӤT��Ϊ��ݪk�B�z (�惡��x��P��, ��ĳ�Ѧ�``97 �Ǧ~��ҼƾǤA''��D C ��ѻ�). �o�O�@�� ASA (�� AAS) ��D, �Y��D�T��Ϊ��T�Ө��M�Y�@��. �G�Q�Υ��w�z ( a/sin A = b/sin B = c/sin C) ��X�A. �ѥ��w�z�i�o

b = $\displaystyle {\frac{\sin B}{\sin C}}$ ×c = $\displaystyle {\frac{\sin 70^\circ}{\sin 30^\circ}}$ ×11 = cos 20^o×22 $\displaystyle \thickapprox$ 20.68.

Li 2008-08-16