2 years ago

I need help figuring out when to use law of sine or law of cosine?

1 answer:

4 0

When you have angle and its corresponding (opposite) side then you need to use law of sin. Problems 3,4,5(in 5 you need at first find angle X=180-92-62)

when you have two sides and angle between them, this is law of cos, problem 6,8

problem 7 you can use both, but if you can use both better to use law of sin, it is just easier

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What’s the least common multiple of x^2-2x-15 and x^2+2x-3?

Ghella [55]

Answer:

$\large\boxed{LCM(x^2-2x-15,\ x^2+2x-3)=(x+3)(x-5)(x-1)}\\\boxed{=x^3-3x^2-13x+15}$

Step-by-step explanation:

$x^2-2x-15=x^2+3x-5x-15=x(x+3)-5(x+3)=(x+3)(x-5)\\\\\\x^2+2x-3=x^2+3x-1x-3=x(x+3)-1(x+3)=(x+3)(x-1)\\\\LCM(x^2-2x-15,\ x^2+2x-3)=(x+3)(x-5)(x-1)\\\\=(x^2-2x-15)(x-1)\qquad\text{use FOIL}\\\\=(x^2)(x)+(x^2)(-1)+(-2x)(x)+(-2x)(-1)+(-15)(x)+(-15)(-1)\\\\=x^3-x^2-2x^2+2x-15x+15\qquad\text{combine like terms}\\\\=x^3+(-x^2-2x^2)+(2x-15x)+15\\\\=x^3-3x^2-13x+15$