Equations
Unfold
Math OP
Fold
Linear algebra
Unfold
Mathematical calculation：
Enter the mathematical formula directly and click the "Next" button to get the calculation answer.
It supports mathematical functions (including trigonometric functions).
Enter the mathematical formula directly and click the "Next" button to get the calculation answer.
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*(cos2*π/7)^2+4*(cos4*π/7)^2+4*(cos8*π/7)^2 .
Question type: Mathematical calculation
Solution:
4*(cos2*π/7)^2+4*(cos4*π/7)^2+4*(cos8*π/7)^2
=4*(-0.186766)^2+4*(cos4*π/7)^2+4*(cos8*π/7)^2
=4*(-0.186766)^2+4*(-0.293355)^2+4*(cos8*π/7)^2
=4*(-0.186766)^2+4*(-0.293355)^2+4*(-0.0653)^2
=4*0.034881538756+4*(-0.293355)^2+4*(-0.0653)^2
=4*0.034881538756+4*0.086057156025+4*(-0.0653)^2
=4*0.034881538756+4*0.086057156025+4*0.00426409
=0.139526+4*0.086057156025+4*0.00426409
=0.139526+0.344229+4*0.00426409
=0.139526+0.344229+0.017056
=0.483755+0.017056
=0.500811
Answer:4*(cos2*π/7)^2+4*(cos4*π/7)^2+4*(cos8*π/7)^2=0.500811
Note: Radian