Question

If cot5#•cot4#=1 then #=?​

Answer 1

Answer:

thank you if you like my answer then follow mi

Step-by-step explanation:

first you can differentiate cot 5=1/tan then cot 4 it also differentiate like these then you can get your answer

Answer 2

$\theta =10$°

Step-by-step explanation:

Given:

$\cot 5\theta.\cot 4\theta=1$

To find , the value of $\theta=?$

∴ $\cot 5\theta.\cot 4\theta=1$

⇒ $\dfrac{\cos 5\theta}{\sin 5\theta}.\dfrac{\cos 4\theta}{\sin 4\theta}=1$

⇒$\cos 5\theta.\cos 4\theta=\sin 5\theta.\sin4\theta$

⇒ $\cos 5\theta.\cos 4\theta-\sin 5\theta.\sin4\theta=0$

⇒ $\cos (5\theta+5\theta)=0$

[∵$\cos (A+B)=\cos A.\cos B-\sin A\sin B$

⇒ $\cos 9\theta=0=\cos 90$

⇒ $9\theta = 90$°

⇒ $\theta$ =$\dfrac{90}{9}$=10°

Hence, $\theta =10$°

You can also see:

https://brainly.in/question/14239162