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求sec50°+tan10°的值.

题目详情
求sec50°+tan10°的值.
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答案和解析
sec50°+tan10°
=
1
cos50°
+
sin10°
cos10°

=
2sin50°
2sin50°cos50°
+
sin10°
cos10°

=
2sin50°
sin100°
+
sin10°
cos10°

=
2sin50°
cos10°
+
sin10°
cos10°

=
2sin50°+sin10°
cos10°

=
sin50°+(sin50°+sin10°)
cos10°

=
sin50°+cos20°
cos10°

=
cos40°+cos20°
cos10°

=
2cos30°cos10°
cos10°

=2cos30°
=
3