	}
			context.strokeStyle="#d64562";
			context.stroke();
			context.closePath();
		}
		write_approximation_formula();
		check_approximation_facts();
		context.fillStyle="#222222";
		if(is_shown("fact_1"))
			context.fillText("Fact 1. Interpolation is a special case of approximation.", 32, 564);
		if(is_shown("fact_2"))
			context.fillText("Fact 2. Approximation works even for constants.", 32, 588);
		if(is_shown("fact_3"))
			context.fillText("Fact 3. You can do weighted approximation by multiplying points