(1)180°-(25°18′+65°56′)=180°-90°74′=179°60′-91°14′=88°46′（2）(31°40′-25°4′30″)x3+28′3″x2 =(31°39′60″-25°4′30″)×3+56′6″=6°35′30″×3+56′6″=18°105′90″+56′6″=18°1...