化简求值2sin50°+cos10°(1+3tan10°)cos35°cos40°+cos50°cos55°.

问题描述:

化简求值

2sin50°+cos10°(1+
3
tan10°)
cos35°cos40°+cos50°cos55°

原式=

2sin50°+cos10°+
3
sin10°
cos35°cos40°+sin35°sin40°
=
2sin50°+2cos50°
cos5°
=
2
2
(
2
2
sin50°+
2
2
cos50°)
cos5°
=
2
2
sin95°
cos5°
=
2
2
cos5°
cos5°
=2
2