Answer: see proof below
<u>Step-by-step explanation:</u>
Given: A + B + C = π and cos A = cos B · cos C
scratchwork:
A + B + C = π
A = π - (B + C)
cos A = cos [π - (B + C)] Apply cos
= - cos (B + C) Simplify
= -(cos B · cos C - sin B · sin C) Sum Identity
= sin B · sin C - cos B · cos C Simplify
cos B · cos C = sin B · sin C - cos B · cos C Substitution
2cos B · cos C = sin B · sin C Addition
Division
2 = tan B · tan C

<u>Proof LHS → RHS</u>
Given: A + B + C = π
Subtraction: A = π - (B + C)
Apply tan: tan A = tan(π - (B + C))
Simplify: = - tan (B + C)

Substitution: = -(tan B + tan C)/(1 - 2)
Simplify: = -(tan B + tan C)/-1
= tan B + tan C
LHS = RHS: tan B + tan C = tan B + tan C 
You need to substitute 9 with every x value in the equation.
So, 3(9)^2-7(9)+11
p(x)= 191
Answer:
two hours and thirteen minutes.
Step-by-step explanation:
count up from 3pm to 5pm to start with. That gives you two hours
we already have 38 minutes, now just subtract the 25 minutes he spent resting.
That leaves you with 2 hours and 13 minutes.
Correct me if I'm wrong I'm currently responding to this at a major lack of sleep lol
The answer would be
y = 4x -14
y +2 = 4(x-3)
y+2 = 4x -12
y = 4x -12 -2
y = 4x -14 (slope intercept form)