2(sin 50°×cos40°+cos 80°×sin 70°) mohon bantuannya segera di jawab!

2 ( sin 50 × cos 40 + cos 80 × sin 70 )

= 2 sin 50 cos 40 + 2 cos 80 sin 70
= ( sin ( 50+40 ) + sin ( 50-40 ) ) + ( sin (80+70) - sin ( 80-70 ) )
= ( sin 90+sin 10 ) + ( sin 150-sin 10 )
= 1 + sin 10 + ½ - sin 10 = 3/2