Respuesta :

b. It's when sinx=0 and cosx=0

Answer: sintheta = Π/2 + nΠ (D)

Step-by-step explanation:

If (sinx)(cosx) = 0...1

Note that sin2x = sinxcosx + cosxsinx = 2sinxcosx

If Sin2x = 2sinxcosx

(sinx)(cosx) = sin2x/2...2

Substituting equation 2 into 1

Sin2x/2 = 0

Sin2x = 0

2x = sin-¹0

2x = 90°

x = 45° = Π/2 (since 180° = Πrad)

General solution to sin function is

Sintheta = nΠ+(-1)^nΠ/2

Sintheta = nΠ+Π/2 (for n = all positive integers)

Sintheta = Π/2 + nΠ (D)