2 years ago

Cos4x = 8 cos^4 x - 8 cos^2 x + 1Please help me prove! :D

1 answer:

3 0

From cos(2x) = 2cos^2(x) -1

cos(4x) = 2[cos(2x)]^2 -1
= 2[2cos(x) -1]^2 -1
= 2[4cos^2(x) - 4cos(x) + 1] -1
= 8cos^2(x) - 8cos(x) + 1

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Yanira is 3 years older than tim and twice as old as hannah. tim is 2 years older than hannah. how old are yanira, tim, and hann

Sati [7]

Y = T+3 (i)
T = H+2 (ii)
Y = 2*H (iiii)

T = H+2 therefore H = T-2

Substitute H=T-2 into (iii)
Y=2*H
Y=2*(T-2)
Y=2T-4

Now substitute that Y into (i)
(i) says Y = T+3
2T-4=T+3
2T-T-4=3
T-4=3
T=3+4
T=7

Then from (i) Y=T+3 = 7+3 =10
Y=10

And from (iii) Y=2*H
If Y = 10, then H = 5

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sveta [45]

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DaniilM [7]

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