Tan (- 7 π / 12),

Tan (- 7 π / 12),

tan(-7π/12)=tan(-7π/12+π)=tan(5π/12)=tan(π/4+π/6)=(tanπ/4+tanπ/6)/(1-tanπ/4tanπ/6)=（1+√3/3）/（1-1*√3/3）=2+√3

Cos195 = - cos15 = - [(root 6 + root 2) / 4] -Can [(root 6 + root 2) / 4] be further simplified?

It is the most simple, there is no need to simplify

If one part of a and one part of B is equal to a plus one part of B, then the value of a part of B plus B part of a is?

A / B + B / a = (a? + B?) / Ab1 / A + 1 / b = 1 / (a + b) (a + b) / AB = 1 / (a + B (a + b)? = ABA A2 + 2Ab + B? = ABA? + B? = - AB (a? + B?) / AB = - 1. Therefore, if one part of a plus one part of B is equal to a plus one part of B, then the value of a part of B plus B part of a is

The values of COS 195 ° and COS 200 ° were determined without calculation

∵180º

How to make the value of one table equal to the formula of another table in Excel

1. Directly copy the formula cell of another table and paste it into this table
2. Direct input:
=Then go to another table and select the cell to be equal to. Press enter

Using sum difference formula to find the function value cos (- 61 π / 12)=

cos(-61π/12)=cos(-6π+11π/12)=cos(11π/12)=cos(3π/12+8π/12)=cos(π/4+2π/3)=cos(π/4)cos(2π/3)-sin(π/4)sin(2π/3)=√2/2*(-1/2-√3/2)=-√2/4-√6/4

Tangent value and angle formula of three functions?

tan（A+B）=(tanA+tanB)/（1-tanA*tanB）

How to set formula or function in Excel table to automatically change the number into the English abbreviation of month! Thank you very much

=CHOOSE(A1,"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec")

Simplify (1 + 4 of A-2) by A-2 of A

The original formula = [(A-2) / (A-2) + 4 / (A-2)] / A / (A-2)
=(a+2)/(a-2)×(a-2)/a
=(a+2)/a

Simplification √ 1 / 3-2=

(√ 3-2) 1 / 2
Multiply by √ 3 + 2
（√3+2 ）/[(√3+2 )(√3-2 )]
= （√3+2 ）/(-1)
= -√3-2