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 
Answer:
0.75
Step-by-step explanation:
Answer:
$1200
Step-by-step explanation:
$4000 x .06 = $240 x 5 years = $1200
Answer:
20 males, 7 females
Step-by-step explanation:
x=males
x-13=females
x+x-13=27
2x-13=27
2x=40
x=20
20-13=7
Answer:
61.27 cm
Step-by-step explanation:
(3.14)(11)(0.5) = 17.27
2+2+20+9+11+17.27 = 61.27