cos(180+60) = cos(240) = cos(180)cos(60) - sin(180)sin(60)
cos(180) = -1sin(180) = 0cos(60) = 0.5sin(60) = √3/2
Therefore,cos(180+60) = -10.5 - 0√3/2 = -0.5
cos(90+60) = cos(150) = cos(90)cos(60) - sin(90)sin(60)
cos(90) = 0sin(90) = 1
Therefore,cos(90+60) = 00.5 - 1√3/2 = -√3/2
Therefore,cos(180+60) - cos(90+60) = -0.5 - (-√3/2)= -0.5 + √3/2= (√3 - 1)/2 ≈ 0.366025.
Therefore, the value of cos(180+60) - cos(90+60) is approximately 0.366025.
cos(180+60) = cos(240) = cos(180)cos(60) - sin(180)sin(60)
cos(180) = -1
sin(180) = 0
cos(60) = 0.5
sin(60) = √3/2
Therefore,
cos(180+60) = -10.5 - 0√3/2 = -0.5
cos(90+60) = cos(150) = cos(90)cos(60) - sin(90)sin(60)
cos(90) = 0
sin(90) = 1
Therefore,
cos(90+60) = 00.5 - 1√3/2 = -√3/2
Therefore,
cos(180+60) - cos(90+60) = -0.5 - (-√3/2)
= -0.5 + √3/2
= (√3 - 1)/2 ≈ 0.366025.
Therefore, the value of cos(180+60) - cos(90+60) is approximately 0.366025.