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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 cos(4/5*π)+cos(8/5*π)+cos(12/5*π)+cos(16/5*π)+cos(20/5*π) .
Question type: Mathematical calculation
Solution:
cos(4/5*π)+cos(8/5*π)+cos(12/5*π)+cos(16/5*π)+cos(20/5*π)
=cos2.513274+cos(8/5*π)+cos(12/5*π)+cos(16/5*π)+cos(20/5*π)
=cos2.513274+cos5.026548+cos(12/5*π)+cos(16/5*π)+cos(20/5*π)
=cos2.513274+cos5.026548+cos7.539822+cos(16/5*π)+cos(20/5*π)
=cos2.513274+cos5.026548+cos7.539822+cos10.053096+cos(20/5*π)
=cos2.513274+cos5.026548+cos7.539822+cos10.053096+cos12.566371
=-0.809017+cos5.026548+cos7.539822+cos10.053096+cos12.566371
=-0.809017+0.309017+cos7.539822+cos10.053096+cos12.566371
=-0.809017+0.309017+0.309017+cos10.053096+cos12.566371
=-0.809017+0.309017+0.309017+-0.809017+cos12.566371
=-0.809017+0.309017+0.309017+-0.809017+1
=-0.5+0.309017+(-0.809017)+1
=-0.190983+(-0.809017)+1
=-1+1
=0
Answer:cos(4/5*π)+cos(8/5*π)+cos(12/5*π)+cos(16/5*π)+cos(20/5*π)=0
Note: Radian