1.

Cos 21°÷sin69°-sin40°÷cos50°​

Answer»

Step-by-step EXPLANATION:

ANSWER:-

We know that

Sin theta = Cos ( 90- theta)

So is the inverse ie

Cos theta = Sin ( 90- theta)

  • So we can write cos 21° as Sin 69°

And ALSO

  • we can write sin 40° as Cos 50°

If we replace the values we GET

Sin 21°/ Sin 21° - cos 50°/ cos 50°

= 1-1

So the answer is ZERO.

SOME IDENTITIES

  • Sin0 = cos(90-0)
  • Cos0= sin(90-0)
  • Tan0 = cot(90-0)
  • Cot0 = tan(90-0)
  • Sec0 = cosec(90-0)
  • Cosec = sec(90-0)
  • These all are complementary of each other
  • Where 0 = theta
  • sin is Inverse of cosec
  • cos is Inverse of sec
  • tan is Inverse of cot
  • And VICE versa are also correct


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