sin9π/4+cos2π/3+tan5π/4的值.

sin9π/4+cos2π/3+tan5π/4
=sin(π/4+2π)-cos(π-2π/3)+tan(π+π/4)
=√2/2-1/2+1
=(1+√2)/2

原式=sin(π/4)－cos(π/3)＋tan(π/4)
=(√2/2)－(1/2)＋1
=(1＋√2)/2

sin9π/4 sin是2π为周期，所以原式等于sinπ/4=根号2 /2
cos2π/3 -0,5这个可以画单位圆做，用诱导公式换成-sin30度也ok
tan5π/4 是以π为周期 所以原式等于tanπ/4，即1
相加可得 即（根号2+1）/2

(2+√2)/2