Here are the proofs for the trigonometric identities:
a) Prove: 1+secxtanx+1−secxtanx=−sin2x2tanx
Assumption: Due to the image clarity, we assume the Right Hand Side (RHS) denominator is 1−sec2x, which makes the identity provable. The identity will be proven as 1+secxtanx+1−secxtanx=1−sec2x2tanx.
Step 1: Start with the Left Hand Side (LHS) and factor out tanx.
LHS=tanx(1+secx1+1−secx1)
Step 2: Combine the fractions inside the parenthesis.
LHS=tanx((1+secx)(1−secx)(1−secx)+(1+secx))
Step 3: Simplify the numerator and multiply the denominators.
LHS=tanx(1−sec2x2)
Step 4: Multiply to get the final expression.
LHS=1−sec2x2tanx
This matches the assumed RHS.
Therefore, LHS=RHS.
b) Prove: 1+cosxsinx−sinx1+cosx=2cscx
Assumption: Due to the image clarity, we assume the operation between the two fractions is addition, not subtraction, which makes the identity provable. The identity will be proven as 1+cosxsinx+sinx1+cosx=2cscx.
Step 1: Start with the LHS and find a common denominator to combine the fractions.
LHS=(1+cosx)sinxsinx⋅sinx+(1+cosx)(1+cosx)
Step 2: Expand the numerator and use the identity sin2x+cos2x=1.
LHS=(1+cosx)sinxsin2x+(1+2cosx+cos2x)
LHS=(1+cosx)sinx(sin2x+cos2x)+1+2cosx=(1+cosx)sinx1+1+2cosx
Step 3: Simplify the numerator by factoring out 2.
LHS=(1+cosx)sinx2+2cosx=(1+cosx)sinx2(1+cosx)
Step 4: Cancel out the common term (1+cosx).
LHS=sinx2
Step 5: Use the identity sinx1=cscx.
LHS=2cscx
This matches the RHS.
Therefore, LHS=RHS.
c) Prove: tan2x+1tan2x−1=1−2cos2x
Step 1: Start with the LHS and express tan2x in terms of sin2x and cos2x.
LHS=cos2xsin2x+1cos2xsin2x−1
Step 2: Combine the terms in the numerator and denominator.
LHS=cos2xsin2x+cos2xcos2xsin2x−cos2x
Step 3: Simplify by canceling cos2x from the numerator and denominator.
LHS=sin2x+cos2xsin2x−cos2x
Step 4: Use the identity sin2x+cos2x=1 in the denominator.
LHS=1sin2x−cos2x=sin2x−cos2x
Step 5: Use the identity sin2x=1−cos2x to express the LHS in terms of cos2x.
LHS=(1−cos2x)−cos2x=1−2cos2x
This matches the RHS.
Therefore, LHS=RHS.
d) Prove: csc2xtan2x−1=tan2x
Step 1: Start with the LHS and express csc2x and tan2x in terms of sinx and cosx.
LHS=(sin2x1)(cos2xsin2x)−1
Step 2: Simplify the product.
LHS=cos2x1−1
Step 3: Use the identity cos2x1=sec2x.
LHS=sec2x−1
Step 4: Use the Pythagorean identity 1+tan2x=sec2x, which implies sec2x−1=tan2x.
LHS=tan2x
This matches the RHS.
Therefore, LHS=RHS.
That's 2 down. 3 left today — send the next one.