sin ² 9π/2+cos²（ -13π/4）-tan²7π/3=sin ²( 4π+π/2)+cos²（ -4π+3π/4）-tan²(2π+π/3)=sin ²( π/2)+cos²（ 3π/4）-tan²(π/3)=1+0.5-3=-1.5