Prove that SinA/(secA tanA-1) CosA/(cosecA cotA-1)=1?
Prove that SinA/(secA tanA-1) CosA/(cosecA cotA-1)=1?
**Proof:**
To prove that SinA/(secA tanA-1) CosA/(cosecA cotA-1) = 1, we need to simplify the expression on the left side of the equation and show that it equals 1.
Let's start by simplifying the expression step by step:
1. Rewrite secA, tanA, cosecA, and cotA in terms of sine and cosine:
- secA = 1/cosA
- tanA = sinA/cosA
- cosecA = 1/sinA
- cotA = cosA/sinA
Substituting these values into the expression, we have:
SinA/(1/cosA * sinA/cosA - 1) * CosA/(1/sinA * cosA/sinA - 1)
2. Simplify the denominators:
- (1/cosA * sinA/cosA - 1) = (sinA - cosA) / cos^2A
- (1/sinA * cosA/sinA - 1) = (cosA - sinA) / sin^2A
Substituting these values back into the expression, we have:
SinA/(sinA - cosA)/cos^2A * CosA/(cosA - sinA)/sin^2A
3. Simplify the expression further:
- Invert the second fraction and multiply:
SinA/(sinA - cosA)/cos^2A * sin^2A/(cosA - sinA)
- Cancel out common factors:
SinA * sin^2A / (sinA - cosA) * cos^2A / (cosA - sinA)
- Rearrange the terms:
sin^3A * cos^2A / ((sinA - cosA) * (cosA - sinA))
- Notice that (sinA - cosA) and (cosA - sinA) are negative of each other:
sin^3A * cos^2A / (-(sinA - cosA) * (sinA - cosA))
- Simplify the expression:
sin^3A * cos^2A / (sinA - cosA)^2
4. Apply the identity sin^2A + cos^2A = 1:
sin^3A * cos^2A / (sinA - cosA)^2 = sin^3A * cos^2A / (1 - 2sinAcosA + cos^2A)
5. Cancel out common factors:
sin^3A / (1 - 2sinAcosA + cos^2A)
6. Apply the identity sinA * sinA * sinA = sin^3A:
sinA * sinA * sinA / (1 - 2sinAcosA + cos^2A)
7. Apply the identity sinA * cosA = 1/2 * sin(2A):
sinA * sinA * sinA / (1 - sin(2A) + cos^2A)
8. Apply the identity 1 - sin(2A) = cos^2A:
sinA * sinA * sinA / cos^2