化简求值2sin50°+cos10°(1+3tan10°)cos35°cos40°+cos50°cos55°.
问题描述:
化简求值
. 2sin50°+cos10°(1+
tan10°)
3
cos35°cos40°+cos50°cos55°
答
原式=
=2sin50°+cos10°+
sin10°
3
cos35°cos40°+sin35°sin40°
=2sin50°+2cos50° cos5°
=2
(
2
sin50°+
2
2
cos50°)
2
2 cos5°
=2
sin95°
2
cos5°
=22
cos5°
2
cos5°
.
2