T tgutberg Full Member 10+ Year Member 5+ Year Member 15+ Year Member Aug 2, 2007 #1 Advertisement - Members don't see this ad Hey Guys Can someone please explain to me why Cos(π/3) = -cos(2π/3)? Thanks! Tom
Advertisement - Members don't see this ad Hey Guys Can someone please explain to me why Cos(π/3) = -cos(2π/3)? Thanks! Tom
Z z3u2 Full Member 10+ Year Member 15+ Year Member Aug 2, 2007 #2 try drawing out the 4 quadrant (CAST thing) you will see that Cos(π/3) = 1/2 = Cos(60) cos(2π/3) = -1/2 = Cos(120) Or you can draw the Cosine graph, you will see the values Upvote 0 Downvote
try drawing out the 4 quadrant (CAST thing) you will see that Cos(π/3) = 1/2 = Cos(60) cos(2π/3) = -1/2 = Cos(120) Or you can draw the Cosine graph, you will see the values
S Streetwolf Ultra Senior Member Verified Member 10+ Year Member Dentist 15+ Year Member Aug 2, 2007 #3 tgutberg said: Hey Guys Can someone please explain to me why Cos(π/3) = -cos(2π/3)? Thanks! Tom Click to expand... Can also use the rule cos(x-y) = cos(x)cos👍 + sin(x)sin👍 cos(pi/3) = cos(pi - 2pi/3) = cos(pi)cos(2pi/3) + sin(pi)sin(2pi/3) Since cos(pi) = -1 and sin(pi) = 0, we're left with cos(pi/3) = -cos(2pi/3) Upvote 0 Downvote
tgutberg said: Hey Guys Can someone please explain to me why Cos(π/3) = -cos(2π/3)? Thanks! Tom Click to expand... Can also use the rule cos(x-y) = cos(x)cos👍 + sin(x)sin👍 cos(pi/3) = cos(pi - 2pi/3) = cos(pi)cos(2pi/3) + sin(pi)sin(2pi/3) Since cos(pi) = -1 and sin(pi) = 0, we're left with cos(pi/3) = -cos(2pi/3)
