Personalized Acute (triangle) Baby Toddler Long Sleeve T-Shirts. Are you a fan of math jokes? Then you'll love this acute baby triangle White Toddler Long Sleeve T-Shirt design! A classic for Fall, Winter and Spring, these long sleeve toddler t-shirts are sure to be a staple in your child's wardrobe. Whether layered or alone, this t-shirt is soft yet durable enough to stand up to your toddler's playtime demands.