how do i find the missing side of a triangle?

Question

the hipotenusis is 20ft and side B is 9ft I am trying to find side A

Answer 1

depends on the triangle. if its a right triangle its a^2+b^2=c^2 (and all the twos mean to square the letters.) and c represents the longest

Answer 2

It depends entirely on what is missing, what you do and do not know, and what method you'd like to use to solve.

If its a right triangle and you know two sides, the Pythagorean Theorem is all you need

If it is a right triangle and you know one side and one angle, the trigonometric functions would suffice

If its not a right triangle then you need to know at least three things, of the three angles and three sides that exist. From that the Law of Sines or the Law of Cosines would work for you.

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In the example given in youre added details, you mention a hypotenuse. They exist only in right triangles and are the longest side. You provide us with two sides and ask us to find the third. This needs only the Pythagorean Theorem.

a² + b² = c²

Where a and b represent the lengths of the shorter two sides and c represents the length of the hypotenuse.

Since the problem says c = 20 and b = 9, we can stick that into the theorem
a² + 9² = 20²
a² + 81 = 400
a² = 319
a = √319 ... this is as accurate as we can get since the root is an irrational number
a ≈ 17.86

Answer 3

It depends. If you know two sides and an angle, you can use the Law of Cosines. c^2 = a^2 + b^2 - 2ab*cos C.
Where C is the angle opposite the unknown side C.
If you know all the angles and one side, you might try the law of sines. Sin A/a = Sin B/b = Sin C/c, where A is the angle opposite side A, B is opposite side b, and C is opposite side c.

Answer 4

Let unknown side be x.
x² + 9² = 20²
x² = 20² - 9²
x² = (20 - 9) (20 + 9)
x² = 11 x 29
x² = 319
x = 19.9

Answer 5

That depends upon kind of triangle and what you are given. If it is a right triangle, and you have two sides, you can use the Pythagorean theorem. If it is not right, and you know trigonometry, you can use law of cosines or law of sines. There are other ways also, again, depending upon what kind of triangle and what you are given.

Answer 6

a2+b2=c2
a2+9^2=20^2
a2+81=400
a2+81-81=400-81
a2/2=319/2
a=159.50