De Moivre's formula tells us that: #(cos theta + i sin theta)^n = cos n theta + i sin n theta# So we find: #(2(cos(pi/3)+i sin(pi/3)))^4 = 2^4(cos((4pi)/3) + i sin ...

Aug 15, 2016 · Trig table of special arcs, and unit circle --> #cos ((-4pi)/3) = cos ((4pi)/3) = cos (pi/3 + pi) = - cos (pi/3) = -1/2#

May 22, 2017 · #cos(-9/4pi) = cos((-2pi)-1/4pi)# #=cos(-2pi)cos(1/4pi) + sin(-2pi)sin(1/4pi)# #=(1)(sqrt2/2) + (0)(sqrt2/2)# ...

Find an answer to your question Cos pi/7. cos 2pi/7. cos 4pi/7 = ? AkshatNasa293 AkshatNasa293 ...

Jul 25, 2017 · #16cos(pi/15)cos((2pi)/5)cos((4pi)/15)cos((8pi)/15)# = #8xx2sin(pi/15)cos(pi/15)xxcos((2pi)/15)cos((4pi)/15)cos((8pi)/15)xx1/sin(pi/15)#

Jun 12, 2018 · We have to prove , #sin((5pi)/18)+cos((4pi)/9)=cos(pi/9)# We take, #LHS=sin((5pi)/18)+cos((4pi)/9)# #color(white)(LHS)=cos(pi/2-(5pi)/18)+cos((4pi)/9)#

Mar 24, 2016 · pi/3 and (4pi)/3 Apply the trig identity: cos a + cos b = 2cos ((a + b)/2).cos ((a - b)/2) cos (x + pi/3) + cos x = 2cos (x + pi/6)cos (pi/6) = 0 Trig table --> cos ...

Apr 1, 2016 · #2 cos A cos B=cos (A+B) + cos (A-B) # # cos A cos B=1/2 (cos (A+B) + cos (A-B)) # #A=(4pi)/3, B = pi/6# # cos ((4pi)/3) cos (pi/6)=1/2 (cos ((4pi)/3+pi/6) + cos ...

Nov 12, 2019 · Minerva sold 450 shares at a market price of rupees 520 she had to pay brokerage of 0.8% find the amount of receive

Jul 4, 2016 · How do you use the sum and difference identities to find the exact value of #cos 15^@#? How do you use the sum and difference identities to find the exact value of cos 75?