Mister Exam

Other calculators

(1-tg(x/2))/(1-ctg(x/2))=2sin(x/2) equation

The teacher will be very surprised to see your correct solution 😉

v

Numerical solution:

Do search numerical solution at [, ]

The solution

You have entered [src]
       /x\           
1 - tan|-|           
       \2/        /x\
---------- = 2*sin|-|
       /x\        \2/
1 - cot|-|           
       \2/           
$$\frac{1 - \tan{\left(\frac{x}{2} \right)}}{1 - \cot{\left(\frac{x}{2} \right)}} = 2 \sin{\left(\frac{x}{2} \right)}$$
Detail solution
Given the equation
$$\frac{1 - \tan{\left(\frac{x}{2} \right)}}{1 - \cot{\left(\frac{x}{2} \right)}} = 2 \sin{\left(\frac{x}{2} \right)}$$
transform
$$\frac{- 2 \sqrt{2} \cos{\left(\frac{x}{2} + \frac{\pi}{4} \right)} + \tan{\left(\frac{x}{2} \right)} - 1}{\cot{\left(\frac{x}{2} \right)} - 1} = 0$$
$$\frac{1 - \tan{\left(\frac{x}{2} \right)}}{1 - \cot{\left(\frac{x}{2} \right)}} - 2 \sin{\left(\frac{x}{2} \right)} = 0$$
Do replacement
$$w = \cot{\left(\frac{x}{2} \right)}$$
Given the equation:
$$\frac{1 - \tan{\left(\frac{x}{2} \right)}}{1 - \cot{\left(\frac{x}{2} \right)}} - 2 \sin{\left(\frac{x}{2} \right)} = 0$$
Use proportions rule:
From a1/b1 = a2/b2 should a1*b2 = a2*b1,
In this case
a1 = 1 - tan(x/2)

b1 = 1 - cot(x/2)

a2 = 2

b2 = 1/sin(x/2)

so we get the equation
$$\frac{1 - \tan{\left(\frac{x}{2} \right)}}{\sin{\left(\frac{x}{2} \right)}} = 2 \left(1 - \cot{\left(\frac{x}{2} \right)}\right)$$
$$\frac{1 - \tan{\left(\frac{x}{2} \right)}}{\sin{\left(\frac{x}{2} \right)}} = 2 - 2 \cot{\left(\frac{x}{2} \right)}$$
Expand brackets in the left part
1+tan+x/2)/sinx/2 = 2 - 2*cot(x/2)

Expand brackets in the right part
1+tan+x/2)/sinx/2 = 2 - 2*cotx/2

This equation has no roots
do backward replacement
$$\cot{\left(\frac{x}{2} \right)} = w$$
substitute w:
The graph
Rapid solution [src]
     -8*pi
x1 = -----
       3  
$$x_{1} = - \frac{8 \pi}{3}$$
     -4*pi
x2 = -----
       3  
$$x_{2} = - \frac{4 \pi}{3}$$
     4*pi
x3 = ----
      3  
$$x_{3} = \frac{4 \pi}{3}$$
     8*pi
x4 = ----
      3  
$$x_{4} = \frac{8 \pi}{3}$$
x4 = 8*pi/3
Sum and product of roots [src]
sum
  8*pi   4*pi   4*pi   8*pi
- ---- - ---- + ---- + ----
   3      3      3      3  
$$\left(\left(- \frac{8 \pi}{3} - \frac{4 \pi}{3}\right) + \frac{4 \pi}{3}\right) + \frac{8 \pi}{3}$$
=
0
$$0$$
product
-8*pi -4*pi 4*pi 8*pi
-----*-----*----*----
  3     3    3    3  
$$\frac{8 \pi}{3} \frac{4 \pi}{3} \cdot - \frac{8 \pi}{3} \left(- \frac{4 \pi}{3}\right)$$
=
       4
1024*pi 
--------
   81   
$$\frac{1024 \pi^{4}}{81}$$
1024*pi^4/81
Numerical answer [src]
x1 = -69.1150383789755
x2 = -100.530964914873
x3 = 33.5103216382911
x4 = -25.1327412287183
x5 = -75.398223686155
x6 = -33.5103216382911
x7 = -50.2654824574367
x8 = -46.0766922526503
x9 = 81.6814089933346
x10 = 50.2654824574367
x11 = -43.9822971502571
x12 = -37.6991118430775
x13 = -16.7551608191456
x14 = 108.908545324446
x15 = 25.1327412287183
x16 = -18.8495559215388
x17 = -8.37758040957278
x18 = -92.1533845053006
x19 = -96.342174710087
x20 = 31.4159265358979
x21 = -56.5486677646163
x22 = 18.8495559215388
x23 = -232.477856365645
x24 = -6.28318530717959
x25 = -62.8318530717959
x26 = -29.3215314335047
x27 = 12.5663706143592
x28 = -54.4542726622231
x29 = 69.1150383789755
x30 = 58.6430628670095
x31 = 56.5486677646163
x32 = 6.28318530717959
x33 = 83.7758040957278
x34 = 37.6991118430775
x35 = -83.7758040957278
x36 = 96.342174710087
x37 = 92.1533845053006
x38 = -31.4159265358979
x39 = 41.8879020478639
x40 = 100.530964914873
x41 = 71.2094334813686
x42 = 94.2477796076938
x43 = 16.7551608191456
x44 = -12.5663706143592
x45 = 54.4542726622231
x46 = -79.5870138909414
x47 = -94.2477796076938
x48 = 67.0206432765823
x49 = 43.9822971502571
x50 = 75.398223686155
x51 = -41.8879020478639
x52 = 62.8318530717959
x53 = 87.9645943005142
x54 = -4.18879020478639
x55 = -20.943951023932
x56 = -81.6814089933346
x57 = -87.9645943005142
x58 = -71.2094334813686
x59 = 4.18879020478639
x60 = 46.0766922526503
x61 = 8.37758040957278
x61 = 8.37758040957278