diff --git a/education/math/MATH1060 (trig)/Addition and Subtraction.md b/education/math/MATH1060 (trig)/Addition and Subtraction.md
index aebf144..a3b4ee6 100644
--- a/education/math/MATH1060 (trig)/Addition and Subtraction.md	
+++ b/education/math/MATH1060 (trig)/Addition and Subtraction.md	
@@ -1,4 +1,4 @@
 Given the formula $\sin(\alpha + \beta)$:
 $$ \sin(\alpha + \beta) = \sin(\alpha)\cos(\beta) + \cos(\alpha)\sin(\beta) $$
 Given the formula $\cos(\alpha + \beta)$:
-$$ \cos(\alpha + \beta) = 
\ No newline at end of file
+$$ \cos(\alpha + \beta) = \cos(\alpha)\cos(\beta) - \sin(\alpha)\sin(\beta) $$