Hi there!
We are given:
cos(7x)cos(4x) = -1 - sin(7x)sin(4x)
Begin by moving all terms with variables to one side:
cos(7x)cos(4x) + sin(7x)sin(4x) = -1
The corresponding trig identity is cos(A - B). Thus:
cos(7x - 4x) = cos(7x)cos(4x) + sin(7x)sin(4x) = -1
cos(3x) = -1
cos = -1 at π, so:
3x = π
x = π/3
We can also find another solution. Let 3π = -1:
3x = 3π
x = π
Thus, solutions on [0, 2π) are π/3 and π.
Answer:
141 square inches
Step-by-step explanation:
Area of a triangle: Base*Height*1/2
Area of a trapezoid: Height * (Base1 +Base2) / 2
Triangle Base = 6
Triangle Height = 8
6*8*1/2 = 24 square inches
Trapezoid Height = 9
Trapezoid Base1 = 16
Trapezoid Base2 = 10
9*(16+10) / 2 = 117 square inches
Total = Area of triangle + Area of trapezoid
Total = 24 + 117 = 141 square inches
The commutative property of addition means we can add two integers in any order. So yes, It would still apply to two negative integers (for example, -2 + -3 and -3 + -2 both equal five)
Group x terms
(2x^2+8x)-12=0
undistribute 2
2(x^2+4x)-12=0
take 1/2 of 4 and square it, add negative and positive of it insde (2^2=4)
2(x^2+4x+4-4)-12=0
factor perfect square
2((x+2)^2-4)-12=0
distribute
2(x+2)^2-8-12=0
2(x+2)^2-20=0
add 20 to both sides
2(x+2)^2=20
divide both sides by 2
(x+2)^2=10
sqrt both sides, remember to take positive and negative root
x+2=+/-√10
minus 2 both sides
x=-2+√10 and -2-√10
