Chapter 2 - Acute Angles and Right Triangles - Section 2.1 Trigonometric Functions of Acute Angles - 2.1 Exercises - Page 52: 29

$\sec$($\theta$ + 15$^{\circ}$) = $\csc$(75$^{\circ}$ - $\theta$ )

$\sec$($\theta$ + 15$^{\circ}$) According to the Cofunction Identities $\sec$$A$ = $\csc$(90$^{\circ}$ - $A$) Therefore: $\sec$($\theta$ + 15$^{\circ}$) = $\csc$(90$^{\circ}$ - 15$^{\circ}$ - $\theta$ ) $\sec$($\theta$ + 15$^{\circ}$) = $\csc$(75$^{\circ}$ - $\theta$ )