The equation cosx=(sqrt 3)/2 is an identity true or false

Acircle has a circumference of 28.36 units what is the diameter of the circle

Can someone answer this question for me

Arestaurant offers delivery for their pizzas. the total cost the customer pays is the price of the pizzas, plus a delivery fee. one customer pays $23 to have 2 pizzas delivered. another customer pays $59 for 6 pizzas. how many pizzas are delivered to a customer who pays $86?