Question

求sin15°+cos15°的值

Answer 1

sin15°+cos15°
=sin(45-30)+cos(45-30)
=sin45°cos30°-cos45°sin30°+cos45°cos30°+ sin45°sin30°
=【(根号2）/2】*（cos30°-sin30°+cos30°-sin30°）
=【(根号2）/2】*（2cos30°）
=【(根号2）/2】*【2*（根号3）/2】
=（根号6）/2

Answer 2

sin15°+cos15°
=√2*(√2/2sin15°+√2/2*cos15°)
=√2*(sin15°cos45°+cos15°sin45°)
=√2*sin(15°+45°)
=√2*sin60°
=√2*√3/2
=√6/2

Answer 3

sin15°+cos15°
=√2sin(15°+45°)
=√2sin60°
=√6/2

Answer 4

(sin15+cos15)^2=1+sin30=3/2
sin15+cos15=根号6/2
（因为sin15°+cos15°>0）

Answer 5

sin15+cos15=genhao2(sin15cos45+cos15sin45)=genhao2sin60=genhao2sin60