Prove that \(\displaystyle\text{arccot}{\frac{{{1}-{x}{\sin{\phi}}}}{{{x}{\cos{\phi}}}}}-\text{arccot}{\frac{{{\cos{\phi}}}}{{{x}-{\sin{\phi}}}}}=\phi\) I used the formula

ropowiec2gkc

ropowiec2gkc

Answered question

2022-03-28

Prove that arccot1xsinϕxcosϕarccotcosϕxsinϕ=ϕ
I used the formula cot(αβ)=cotαcotβ+1cotαcotβ with α=arccot1xsinϕxcosϕ and β=arccotcosϕxsinϕ.
What I got is as it follows:
1xsinϕxcosϕ.cosϕxsinϕ+11xsinϕxcosϕcosϕxsinϕ
And after some calculations I got that it's equal to:
(1xsinϕ+xsinϕ)cosϕxsinϕx2sinϕ+xsin2ϕxcos2ϕ

Answer & Explanation

Jadyn Gentry

Jadyn Gentry

Beginner2022-03-29Added 12 answers

The approach is right, but you've made a mistake somewhere.
cot(αβ)=1xsinϕxcosϕcosϕxsinϕ+1cosϕxsinϕ1xsinϕxcosϕ
=(1xsinϕ)cosϕ+xcosϕ(xsinϕ)xcos2ϕ(1xsinϕ)(xsinϕ)
=cosϕ(1xsinϕ+x2xsinϕ)x(1sin2ϕ)x+sinϕ+x2sinϕxsin2ϕ
=cosϕ(1+x22xsinϕ)2xsin2ϕ+sinϕ+x2sinϕ
=cosϕ(1+x22xsinϕ)sinϕ(1+x22xsinϕ)
=cosϕsinϕ
=cotϕ

Do you have a similar question?

Recalculate according to your conditions!

Ask your question.
Get an expert answer.

Let our experts help you. Answer in as fast as 15 minutes.

Didn't find what you were looking for?