eliminate θ~ ATGS stuck in a basic sum! :(

eliminate θ from the foll eqns.:

cosecθ - sinθ = m

secθ - cosθ=n

i couldnt do this! :(

6 Answers

49
Subhomoy Bakshi ·

pata hai ki its very easy,....

i had solved it earlier...

but can't do now at ne cost! :(

will u plz show the soln?? please??

1
Abhisek ·

cosecθ - sinθ = m
or, cosec2θ + sin2θ - 2 = m2 (By squaring) ............(i)

secθ - cosθ = n
or, sec2θ + cos2θ - 2 = n2 (By squaring) .............................(ii)

(i)+(ii)
=> cosec2θ + sec2θ + sin2θ + cos2θ - 4 = m2+ n2

=> cosec2θ + sec2θ + 1 - 4 = m2+n2

=> cosec2θ + sec2θ - 3 = m2+n2

=> sin2θ + cos2θsin2θcos2θ - (m2+n2) = 3

=> 1sin2θcos2θ - (m2+n2) = 3..........................(iii)

Now,
cosecθ - sinθ = m
or, 1-sin2θsinθ = m

or, cos2θsinθ = m...........(a)

Similarly, sin2θcosθ = n......(b)

Multiplying (a) and (b) , we get sinθcosθ = mn

Substitute the values of sinθcosθ in (iii) and simplify to get the answer... [12]

Phew!

1
nihal raj ·

for the first equation

m2/3 + n2/3n2/3 - √n2/3m2/3+n2/3 = m

for the second equation

m2/3 + n2/3m2/3 - √m2/3m2/3+n2/3 = n

subho are they correct...........

1
Abhisek ·

@ Subho
@ Nihal
@ everyone else...

When we are given a problem like "eliminate θ from these two equations, does that mean we have to frame a single equation or two separate equations (in which θ is eliminated) ?

The way I did was by forming a joint degree-two equation...

Nihal formed two linear equations....

Which is the required / preferred method ?

49
Subhomoy Bakshi ·

meaning is same!

u have to find relation b/w m and n here!

so u give 1 relation or 2its all the same!

like if u tell he is my grandfather or say he is my father's father its all the same!! [1]

1
Abhisek ·

By the way is it correct ?

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