Duplicate Question
The question on this page has been marked as a duplicate question.
Original Question
if sinA=-(12/13) and -90<A<0, find without using calcuator, the value of cot(90-A)Asked by AlexMaths
if sinA=-(12/13) and -90<A<0, find without using calcuator, the value of cot(90-A)
Answers
Answered by
nms
cot(90-A)= -2.40 approximately
use arcsinA or 1/sinA =-(12/13) to get the value of A..or use sine graph..to get the answer.
cotangent=cosx/sinx..
just input the value of A which is -67.38 to that of formula above with x as (90-A)...
use arcsinA or 1/sinA =-(12/13) to get the value of A..or use sine graph..to get the answer.
cotangent=cosx/sinx..
just input the value of A which is -67.38 to that of formula above with x as (90-A)...
Answered by
Reiny
It said "without a calculator"
All the work following is done in my head.
sinA = -12/13 = y/r
x^2 + y^2 = r^2
x^2 + (-12)^2 = 13^2
x^2 + 144 = 169
x^2 = 25
x = ± 5 , but A is in quad IV, so x = 5
so sinA = -12/13, cosA = +5/13
tanA = (-12/13) / (5/13) = -12/5
since cot(90-A) = tanA
<b>cot(90-A) = -12/5 = -2.4</b>
(exactly, not approximately)
All the work following is done in my head.
sinA = -12/13 = y/r
x^2 + y^2 = r^2
x^2 + (-12)^2 = 13^2
x^2 + 144 = 169
x^2 = 25
x = ± 5 , but A is in quad IV, so x = 5
so sinA = -12/13, cosA = +5/13
tanA = (-12/13) / (5/13) = -12/5
since cot(90-A) = tanA
<b>cot(90-A) = -12/5 = -2.4</b>
(exactly, not approximately)
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.