lsugano
what is cot2a=0 Thus 2a=90˚....how did this happen?



This Question is Closed

Mimi_x3
Best Response
You've already chosen the best response.
1
\[ cot2a = 0 => \frac{cos2a}{sin2a} = 0 => cos2a = 0 => 2a = cos(0)\]

Mimi_x3
Best Response
You've already chosen the best response.
1
wait i made a typo:
\[ 2a = cos^{1}(0)\]

Mimi_x3
Best Response
You've already chosen the best response.
1
since you know that \(cos^{1}(0) = 90\)

Mimi_x3
Best Response
You've already chosen the best response.
1
then \( 2a = 90\)

lsugano
Best Response
You've already chosen the best response.
0
wait how did cot2a= cos2a/sin2a?

waterineyes
Best Response
You've already chosen the best response.
0
Firstly you should remember that:
\[\cos(90) = 0\]

Mimi_x3
Best Response
You've already chosen the best response.
1
because \[ cota = \frac{cosa}{sina}\]

waterineyes
Best Response
You've already chosen the best response.
0
*cot

waterineyes
Best Response
You've already chosen the best response.
0
\[\large \cot(90^{\circ}) = 0\]

waterineyes
Best Response
You've already chosen the best response.
0
So you can replace 0 with cot(90):
\[\cot(2a) = \cot(90)\]

lsugano
Best Response
You've already chosen the best response.
0
im sorry but isnt cot= 1/tana?

Mimi_x3
Best Response
You've already chosen the best response.
1
well you can use that method if you remember whats cot(90)

waterineyes
Best Response
You've already chosen the best response.
0
Now as trigonometric ratio is same:
So you can equate the angles:
\[2a = 90\]

Mimi_x3
Best Response
You've already chosen the best response.
1
yes it because what tana?

Mimi_x3
Best Response
You've already chosen the best response.
1
what is*

Mimi_x3
Best Response
You've already chosen the best response.
1
yes it is but whats tan(a) then?*

lsugano
Best Response
You've already chosen the best response.
0
oh cot also equals to x/y so cos/sin right??

waterineyes
Best Response
You've already chosen the best response.
0
Right..

lsugano
Best Response
You've already chosen the best response.
0
ohhhh okay it makes sense

lsugano
Best Response
You've already chosen the best response.
0
so i get that cos2a/sin2a = 0 but then what is next?

Mimi_x3
Best Response
You've already chosen the best response.
1
i typed the solution for you already..

waterineyes
Best Response
You've already chosen the best response.
0
Multiply by sin(2a) both the sides..

lsugano
Best Response
You've already chosen the best response.
0
so it becomes cos2a (sin2a) = 0 (sin2a)

waterineyes
Best Response
You've already chosen the best response.
0
No..
There is one sin(2a) in the denominator too..

waterineyes
Best Response
You've already chosen the best response.
0
Can't you cancel sin(2a) with sin(2a) on left hand side ??

lsugano
Best Response
You've already chosen the best response.
0
so does it become like this?

waterineyes
Best Response
You've already chosen the best response.
0
Yep..

lsugano
Best Response
You've already chosen the best response.
0
oh okay now i get the steps! thank you so much @waterineyes @Mimi_x3

waterineyes
Best Response
You've already chosen the best response.
0
Welcome dear..