3 years ago

Which pair of numbers is relatively prime? A. 5 and 75 B. 12 and 51 C. 7 and 20 D. 15 and 21

Mathematics

2 answers:

Zielflug [23.3K]3 years ago

8 0

The only number not divisible by anything except itself and 1, was C. 7

bonufazy [111]3 years ago

5 0

The answer is C 7 and 20

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Find AD. Show how you got your answer.

stealth61 [152]

Notice the picture below
the AD line is a bisector, cutting the 36 degrees A in half,
18 and 18 degrees each half

notice the tickmarks, the triangle is an isosceles,
if those two sides are equal, so are the angles they make
down below with the base

now, the base is 8, AD is bisecting that too, to 4 and 4

now, using the Law of Sines

$\bf \textit{Law of sines}
\\ \quad \\
\cfrac{sin(\measuredangle A)}{a}=\cfrac{sin(\measuredangle B)}{b}=\cfrac{sin(\measuredangle C)}{c}\\\\
----------------------------\\\\
\cfrac{sin(18^o)}{4}=\cfrac{sin(72^o)}{\overline{AD}}\implies \overline{AD}=\cfrac{4\cdot sin(72^o)}{sin(18^o)}$

keep in mind, the angles are in degrees, so, when taking the sines, make sure your calculator is in Degree mode