An equilateral triangle has an altitude of 21 inches. What is the side
1 answer:
Answer:
7
Step-by-step explanation:
the altitude creates two congruent 30-60-90° triangles
the ratio of the sides in a 30-60-90°, respectively, are 1 : : 2
therefore we can set up a proportion to find the side length:
let 'x' = side length of equilateral Δ
/ 1 = 21 / x
cross-multiply:
x = 21
x = 21 /
rationalize the denominator by multiplying numerator and denominator by
21 /
·
= 21
/ 3 or 7
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Answer:
Step-by-step explanation:
Cosine is the adjacent side over the hypotenuse (You can remember sin, cos, and tan by using sohcahtoa or sin = opposite/hypotenuse, cos = adjacent/hypotenuse, tan = opposite over adjacent). I think a picture would help, too.
I attached a picture of what I think the triangle would look like.
If the picture is right (we're assuming it is) and going with what we're given (the triangle was addressed as triangle XYZ, meaning that <u>angle Y is in the middle and that's the one we'll use</u>).
Looking at my picture then:
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