Question

If sin A sin B - cos A cos B +1 =0 ,prove that 1+cot A tan B = 0

Answer 1

we just need to prove that sin A cos B - cos A sin B +1 = sin(A+b)

Answer 2

thats what i can't do!

Answer 3

take the right side.

Answer 4

pls elaborate

Answer 5

recheck the question.

Answer 6

k it was a cos instyead of sin corrected

Answer 7

then edit the question .

Answer 8

did i t already , maybe refres
h

Answer 9

oooh so the question was wrong, I was really confused

Answer 10

yeah my mistk sry :)

Answer 11

sin A cos B - cos A cos B +1 =0 ,prove that 1+cot A tan B = 0

Answer 12

??
see the ques...

Answer 13

yes

Answer 14

any further progress ..

Answer 15

the question ?! is there a problem with the question ?!

Answer 16

nope ques is "If sin A sin B - cos A cos B +1 =0 ,prove that 1+cot A tan B = 0" and nothin else

Answer 17

maybe the ques in my book is wrong ...

Answer 18

\[ \sin A \sin B - \cos A \cos B + 1 = 0 \\ \cos (A+B) = 1 \\ \text{which implies} \\ \sin (A+B) = 0 \\ \sin A \cos B + \sin B \cos A = 0 \\ 1 + \cot B \tan A = 0\] but this answer is only valid if \[A + B = 90^\circ\] I think

Answer 19

how does 2nd line imply 4th one?

Answer 20

you don't know this formula sin(A+B)=sin(A)cos(B)+sin(B)cos(A) @problemsolver

Answer 21

i know ..

Answer 22

but how does sin(A)cos(B)+sin(B)cos(A) = cosA cos B - sinA sinB -1

Answer 23

k.. i understand you used that in(90-A) =cos(A)..right??

Answer 24

there's an s before in(90-A)

Answer 25

A and B are not any real numbers ....they satisfy cos(A+B)=1 !
So the answer of @AugustinusSextus is correct except the last thing ! ! for the 5'th lin===>6th line ! He divided by sin(B)cos(A) both sides ! clear now ?!

Answer 26

hahaha oops my mistake, but it's still valid tho :p

Answer 27

can you show me how to type statements with latex (like implies....) !:) please :) @AugustinusSextus

Answer 28

k.. thanks both of you