数学推理sin10+cos40+sin10cos40=3/4,sin6+c0s36+sin6cos36=3/4猜想规律,并证明之

题目有误 sin^2 10+cos^2 40+sin 10cos40=3/4sin^2 6+cos^2 36+sin6 cos36=3/4(sina)^2+(cos(a+30))^2+sinacos(a+30)=3/4证明:(sina)^2+[cos(a+30)]^2+sinacos(a+30)=(1-cos2a)/2+[1+cos(2a+60)]/2+sina(cosacos30-s...