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It supports mathematical functions (including trigonometric functions).
Current location：Mathematical operation > History of Mathematical Computation > Answer
Overview: 1 questions will be solved this time.Among them
☆1 arithmetic calculations
[1/1 Formula]
Work: Calculate the value of equation 4*(cos(2*π/7))^2+4*(cos(4*π/7))^2+4*(cos(8*π/7))^2 .
Question type: Mathematical calculation
Solution:
4*(cos(2*π/7))^2+4*(cos(4*π/7))^2+4*(cos(8*π/7))^2
=4*(cos0.897598)^2+4*(cos(4*π/7))^2+4*(cos(8*π/7))^2
=4*0.62349^2+4*(cos(4*π/7))^2+4*(cos(8*π/7))^2
=4*0.62349^2+4*(cos1.795196)^2+4*(cos(8*π/7))^2
=4*0.62349^2+4*(-0.222521)^2+4*(cos(8*π/7))^2
=4*0.62349^2+4*(-0.222521)^2+4*(cos3.590392)^2
=4*0.62349^2+4*(-0.222521)^2+4*(-0.900969)^2
=4*0.3887397801+4*(-0.222521)^2+4*(-0.900969)^2
=4*0.3887397801+4*0.049515595441+4*(-0.900969)^2
=4*0.3887397801+4*0.049515595441+4*0.811745138961
=1.554959+4*0.049515595441+4*0.811745138961
=1.554959+0.198062+4*0.811745138961
=1.554959+0.198062+3.246981
=1.753021+3.246981
=5.000002
Answer:4*(cos(2*π/7))^2+4*(cos(4*π/7))^2+4*(cos(8*π/7))^2=5.000002
Note: Radian