Question

(Sin²A - I ) × cosec ² ( 90- A)​

Answer 1

Answer:

Step by step solution:

Cosec²(90-A)= Sec²A = 1/Cos²A

Sin²A-1 = Sin²A -(Sin²A +Cos²A) = -Cos²A

Substituting these values in question, we get

-Cos²A × 1/Cos²A = -1

One must learn basic trigonometry identities and practice a lot to be master at trigonometry.

The identities used in this question

• Cos(90-x) = sinx
• sin²x + cos²x = 1
• Sec x= 1/cos x