Question

find the value of COS2pie/5 ​

Answer 1

Answer:

1 is the answer i guess i hope it helps you

Answer 2

Step-by-step explanation:

cos( 2pi / 5)

= cos ( (2×180)÷ 5)

= cos (360÷ 5)

= cos (72°)

= cos (90°-18°)

= cos 90°cos18°+ sin90°sin18°

= 0 × cos18°+ 1× sin18°

= sin18°

=

$\frac{ \sqrt{5} - 1 }{4}$