I want to get this app for my son so he can help my granddaughter with math. Will there be a cost at some point? also, would I use email to send it to him? It is one of the gifts I'm giving him for his birthday.

The app is completely free! You have access to answering questions, posting questions, and even getting Brainliest (a reward for the best answer in a question). However, it's optional to pay for something called " Plus". Plus gives you things like unlimited access to questions with verified answers and an uninterrupted experience (no advertisements).

Step-by-step explanation:

answer would be 8.64 or s = 11π/4 inches

step-by-step explanation:

s = r θ  

where s = arc length  

r = radius = 3 inches  

θ = central angle in radians = ( π /180)*165  

s = 3(π/180)*165  

= 8.64 inches