计算:sin47°−sin17°cos30°cos17°=_.
问题描述:
计算:
=______. sin47°−sin17°cos30° cos17°
答
原式=
sin(30°+17°)−sin17°cos30° cos17°
=
sin30°cos17°+cos30°sin17°−sin17°cos30° cos17°
=
=sin30°=sin30°cos17° cos17°
.1 2
故答案为:
1 2