How to see (visualize) the robot orientation (Yaw) in rviz

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Hello

I need a help regarding a robot orientation. I made a node that calculate the orientation of the robot to some object in the map/ So I can get the Yaw from my transformation, but that is just a number. Is there any tool that can visualize that orientation??This the part of the code where I get the YAW

.... some code.. while (node.ok()) {

            //Speed and Yaw calculation
            tf::StampedTransform transform2;
        if(speed_count==9)
        {
                try{
                    listener.lookupTransform("/map", "/base_link",  
                                ros::Time(0), transform2);

                }
                    catch (tf::TransformException ex){};

                vel = hypotenuse(xlast,ylast, transform2.getOrigin().x(),transform2.getOrigin().y());
            if(vel<0.003){
                yaw = tf::getYaw(transform2.getRotation());
            }

            speed_count = 0;
            xlast = transform2.getOrigin().x(); ylast = transform2.getOrigin().y();
        }
        else speed_count++;

..... more code

Any help??