diff --git a/libraries/AC_WPNav/AC_Circle.cpp b/libraries/AC_WPNav/AC_Circle.cpp
index 1943bf8893..a9cdb99e00 100644
--- a/libraries/AC_WPNav/AC_Circle.cpp
+++ b/libraries/AC_WPNav/AC_Circle.cpp
@@ -35,9 +35,7 @@ AC_Circle::AC_Circle(const AP_InertialNav& inav, const AP_AHRS& ahrs, AC_PosCont
     _ahrs(ahrs),
     _pos_control(pos_control),
     _last_update(0),
-    _angle(0),
-    _cos_yaw(1.0),
-    _sin_yaw(0.0)
+    _angle(0)
 {
     AP_Param::setup_object_defaults(this, var_info);
 }
@@ -66,8 +64,8 @@ void AC_Circle::init_center()
     _pos_control.get_stopping_point_z(stopping_point);
 
     // set circle center to circle_radius ahead of stopping point
-    _center.x = stopping_point.x + _radius * _cos_yaw;
-    _center.y = stopping_point.y + _radius * _sin_yaw;
+    _center.x = stopping_point.x + _radius * _ahrs.cos_yaw();
+    _center.y = stopping_point.y + _radius * _ahrs.sin_yaw();
     _center.z = stopping_point.z;
 
     // update pos_control target to stopping point
diff --git a/libraries/AC_WPNav/AC_Circle.h b/libraries/AC_WPNav/AC_Circle.h
index 1f2e99759d..b877cdbc6f 100644
--- a/libraries/AC_WPNav/AC_Circle.h
+++ b/libraries/AC_WPNav/AC_Circle.h
@@ -47,12 +47,6 @@ public:
     int32_t get_pitch() const { return _pos_control.get_pitch(); };
     int32_t get_yaw() const { return _yaw; };
 
-    /// set_cos_sin_yaw - short-cut to save on calculations to convert from roll-pitch frame to lat-lon frame
-    void set_cos_sin_yaw(float cos_yaw, float sin_yaw) {
-        _cos_yaw = cos_yaw;
-        _sin_yaw = sin_yaw;
-    }
-
     static const struct AP_Param::GroupInfo var_info[];
 
 private:
@@ -86,9 +80,5 @@ private:
     float       _angular_vel;   // angular velocity in radians/sec
     float       _angular_vel_max;   // maximum velocity in radians/sec
     float       _angular_accel; // angular acceleration in radians/sec/sec
-
-    // helper variables
-    float       _cos_yaw;       // short-cut to save on calcs required to convert roll-pitch frame to lat-lon frame
-    float       _sin_yaw;       // To-Do: move these to ahrs or attitude control class to save on memory
 };
 #endif	// AC_CIRCLE_H