Question

cos^4 π/8+ cos^4 3π/8+cos^4 5π/8 +cos^4 π/8= 3/2​

Answer 1

Answer:

cos

4

(π/8)+cos

4

(3π/8)+cos

4

(π−

8

3π

​

)+cos

4

(π−

8

π

​

)−3/2

=cos

4

(π/8)+cos

4

(3π/8)+cos

4

(π/8)+cos

4

(3π/8)−3/2

=2cos

4

(π/8)+2cos

4

(3π/8)−3/2

=2[cos

4

(π/8)+cos

4

(3π/8)]−3/2

=2[(0.9238)

4

+(0.38268)

4

]−3/2

=2[0.72855+0.02144]−1.5

=1.5−1.5

=0

Answer 2

Answer:

cos4(π/8) + cos4(3π/8) + cos4(π - 3π8) + cos4(π - π8) - 3/2 = cos4(π/8) + cos4(3π/8) + cos4(π/8) + cos4(3π/8) - 3/2 = 2cos4(π/8) + 2cos4(3π/8)