diff --git a/include/gp/math/fp_math.hpp b/include/gp/math/fp_math.hpp
index 0275639..7417920 100644
--- a/include/gp/math/fp_math.hpp
+++ b/include/gp/math/fp_math.hpp
@@ -154,9 +154,21 @@ namespace gp{
 
 	// TODO: replace with an actual implementation
 	double cos(double v) {
-		return sin(v+pi<float>/2);
+		return sin(v+pi<double>/2);
 	}
 
+	// TODO: replace with an actual implementation
+	float tan(float v) {
+		return sin(v)/cos(v);
+	}
+
+	// TODO: replace with an actual implementation
+	double tan(double v) {
+		return sin(v)/cos(v);
+	}
+
+
+
 	template<size_t cycles = 5>
 	float isqrt(float v) {
 		int32_t i;