No, this is the underside of an orbweaver type of spider. I’m not sure which species. It is not dangerous. They only have about as much venom as a bee. Like honeybees they won’t hurt you unless they feel endangered, such as being squashed against your skin . The things that really set it apart from a brown widow are: its bright orange patch, the orbweaver black/white/yellow marking on the ventral surface, and the X shape some orbweavers bodies form at rest.