Why does the red triangle handbrake on warning light come on in a Corsa when turning right It goes off when the wheels straighten and doesn't happen when I turn left and the steering feels fine?

Answer 1

It also indicates low brake fluid which presumably moves off the sensor as you corner; the level may have fallen due to a leak or will fall as the disc brake pads wear allowing the calipers to extend further. Check the fluid level and look for leaks around the front and rear brakes.