What is the formula for sin (θ / 2) The one with the double angle

This is the half angle formula
tan^2(α/2)=(1-cosα)/(1+cosα)
Sin (α / 2) = ± [(1-cos α) / 2] ^ (1 / 2)
Cos (α / 2) = ± [(1 + cos α) / 2] ^ (1 / 2)
tan(α/2)=sinα/(1+cosα)=(1-cosα)/sinα=±[(1-cosα）/（1+cosα）]^(1/2)
Derivation: Tan (α / 2)
=sin（α/2） /cos（α/2）
=[2sin（α/2）cos（α/2] /2cos(α/2)^2
=sinα/(1+cosα)
=(1-cosα)/sinα

What's the formula for π / 2 sin π / 2

Ask the book... π / 2 sin π / 2 = π / 2 want to know how to calculate... Find a formula.. from: help to get the answer answer: because sin π / 2 = 1 this value is calculated by the sine image, you can also use the sine line to calculate this value, and usually you only need to recite this number down, often used In this way, your formula is equal to the following value π / 2

Find the formula of sin a / 2,

sin(α/2)=±[(1-cosα)/2]½
If the first two quadrants are positive, the third and fourth quadrants are negative
sinα=2sin1/2αcos1/2α=2tanα/(1+tan²α)

On the formula of a, B, sin It is proved that if the radius of the circumscribed circle of a triangle is r, then a = 2sina, B = 2sinb, C = 2sinc

Trigonometric function formula
Sum of two angles formula
sin(A+B)=sinAcosB+cosAsinB sin(A-B)=sinAcosB-sinBcosA
cos(A+B)=cosAcosB-sinAsinB cos(A-B)=cosAcosB+sinAsinB
tan(A+B)=(tanA+tanB)/(1-tanAtanB) tan(A-B)=(tanA-tanB)/(1+tanAtanB)
ctg(A+B)=(ctgActgB-1)/(ctgB+ctgA) ctg(A-B)=(ctgActgB+1)/(ctgB-ctgA)
Double angle formula
tan2A=2tanA/(1-tan2A) ctg2A=(ctg2A-1)/2ctga
cos2a=cos2a-sin2a=2cos2a-1=1-2sin2a
Half angle formula
sin(A/2)=√((1-cosA)/2) sin(A/2)=-√((1-cosA)/2)
cos(A/2)=√((1+cosA)/2) cos(A/2)=-√((1+cosA)/2)
tan(A/2)=√((1-cosA)/((1+cosA)) tan(A/2)=-√((1-cosA)/((1+cosA))
ctg(A/2)=√((1+cosA)/((1-cosA)) ctg(A/2)=-√((1+cosA)/((1-cosA))
Sum difference product
2sinAcosB=sin(A+B)+sin(A-B) 2cosAsinB=sin(A+B)-sin(A-B)
2cosAcosB=cos(A+B)-sin(A-B) -2sinAsinB=cos(A+B)-cos(A-B)
sinA+sinB=2sin((A+B)/2)cos((A-B)/2 cosA+cosB=2cos((A+B)/2)sin((A-B)/2)
tanA+tanB=sin(A+B)/cosAcosB tanA-tanB=sin(A-B)/cosAcosB
ctgA+ctgBsin(A+B)/sinAsinB -ctgA+ctgBsin(A+B)/sinAsinB
Sine theorem
1. A / Sina = B / SINB = C / sinc = 2R (2R is a constant in the same triangle, which is twice the radius of the circumcircle of the triangle). For any triangle ABC, there is a / Sina = B / SINB = C / sinc = 2R, and R is the radius of the circumcircle of the triangle
2. S △ ABC = (AB / 2) · sinc = (BC / 2) · Sina = (AC / 2) · SINB = ABC / (4R) [R is circumcircle radius]
3、S△ABC=ah/2
4、a=2RsinA,b=2RsinB,c=2RsinC;
5、sinA :sinB :sinC = a :b :c;
6. A / Sina = B / SINB = C / sinc = (a + b) / (Sina + SINB) = (a + B + C) / (Sina + SINB + sinc) (this is sum ratio theorem)
7、sinA=a/2R,sinB=b/2R,sinC=c/2R
8、asinB=bsinA,bsinC=csinB,asinC=csinA
Cosine theorem
In △ ABC, if the opposite side of AB is C, the opposite side of BC is a, and the opposite side of AC is B, then:
a^2=b^2+c^2-2bccosA
b^2=a^2+c^2-2accosB
c^2=a^2+b^2-2abcosC
When C is a right angle, COSC = 90
There is C ^ 2 = a ^ 2 + B ^ 2
Cosine theorem is the general form of Pythagorean theorem
o(∩_ Hope it can help you,

If α, β ∈ (0,2 / π). Cos (α - β / 2) = √ 3 / 2, sin (α / 2 - β) = - 1 / 2, then what is cos (α + β) equal to?

cos(α+β)=cos[(2α-β)-(α-2β)]
And ∵ cos (2 α - β) = Cos2 (α - β / 2)
sin(α-2β)=sin2(α/2-β)
The problem is solved by using the double angle formula and the positive and negative values of trigonometric function values in each quadrant
cos(α+β)
=cos[(2α-β)-(α-2β)]
=cos(2α-β)cos(α-2β)+sin(2α-β)sin(α-2β)
cos(2α-β)=2cos²(α-β/2）-1=1/2
Sin (2 α - β) = √ 3 / 2 (2 α - β ∈ (0, π / 2) is positive in the second quadrant.)
∵ sin (α / 2 - β) = - 1 / 2 (α / 2 - β ∈ (- π / 4,0) in the fourth quadrant,

In the induction formula, sin (180 + a) = - Sina cos (180 + a) = - cos says that a here can be any angle. If a here is equal to 120 degrees, then In the induction formula, sin (180 + a) = - Sina cos (180 + a) = - cos says that a here can be any angle. If a here is equal to 120 degrees, then it is equal to 300 degrees. That's wrong. 300 degrees is the fourth quadrant. Sin (180 + a) = - Sina cos (180 + a) = cos. The function value is wrong... Cosa is positive. What is the meaning of any angle here 2. Supplement of the above; sin (180 + a) = - Sina cos (180 + a) = Coosa If the tangent angle of 120 is 60?; if a is 120 degrees, then Sina (180 + 120) = sin120? = sin60? Can you write this way? Cos (180 + 120) = cos120 = - cos60; please help me to explain the understanding of any angle here! There is one other answer Any angle is only all angles! Your 120 degree is not contradictory. Cos 300 is positive and COS 120 is negative, so there is cos (180 + a) = - cosa There is one other answer 1 answer in total sin(180+a)= -sina；cos(180+a)= -cosa A is an acute angle Is it true that the angle a in sin (180 + a) = - Sina; cos (180 + a) = - cosa is an acute angle?

Sin (180 + a) = - Sina; cos (180 + a) = - cosa 0 ° ≤ a ≤ 90 ° if a is not in this range, it must be converted into an angle in this range before the formula can be used

It is known that sin α = 2 Then cos (π - 2 α) = () A. - Five Three B. -1 Nine C. 1 Nine D. Five Three

∵sina=2
3，
∴cos（π-2a）=-cos2a=-（1-2sin2a）=-1
9．
Therefore, B

What does exp of scientific calculator mean

10 to the power of X
A exp B = a times 10 to the B power

How to press it with calculator exp (2.955) = 19.2 I know that if I press ln 19.2 on the calculator, I get 2.955, but how can I get 19 from 2.955

Press exp first (second in last line)
Then press X ^ y (third to last line, fourth)
Press 2.955 again
Finally, press =

What does the formula exp mean? How to calculate it with a calculator

Exp (a) is e to the power of A
Scientific calculators all have buttons for calculating the nth power of E

What is the formula for sin (θ / 2) The one with the double angle