Trae is searching for a treasure on the beach. From point $A$, he is told to walk two meters north, three meters east, and then two meters north to point $B$. In meters, what is the length of $\overline{AB}$?

A triangle ABC with positive integer side lengths has perimeter 35, centroid G, and incenter I. If ∠GIC=90∘, what is the length of AB¯¯¯¯¯¯¯¯?

We use barycentric coordinates with reference triangle △ABC. Letting k=a+b+c, we have the displacement vectors GI→=(13−ak,13−bk,13−ck) and IC→=(ak,bk,ck−1). EFFT gives us

a2(4b+c3k−13−2bck2)+b2(4a+c3k−13−2ack2)+c2(a+b3k−2abk2)=0

. Multiplying by 3k2, writing k=a+b+c, and expanding out, the equation turns into

a2((a+b+c)(3b−a)−6bc)+b2((a+b+c)(3a−b)−6ac)+c2((a+b)(a+b+c)−6ab)=0.

Expanding further and factoring an a+b+c out, we have

(a+b+c)((a+b)(4ab−a2−b2+c2)−6abc)=0.

Notice that when c=a+b the term (a+b)(4ab−a2−b2+c2)−6abc) vanishes, so we factor further to obtain

(a+b+c)(c−a−b)(a2+b2+c(a+b)−4ab)=0⟹a2+b2+c(a+b)−4ab=0⟹(a+b)2+c(a+b)=6ab⟹35(35−c)=6ab.

From the triangle inequality, we have c≤17 and we also know 6|35−c; it's now easy to find a triple (a,b,c)=(10,14,11) satisfying the equation above, and the answer is 11.

Hope this helps

5   1/4   miles per hour

step-by-step explanation:

15   3/4 / 3 = 5   1/4