so there's a right triangle

90 degrees in the bottom left

30 degrees bottom right

15 in length

unknown adjacent

unknown hypotenuse

so i did sin(30) = 15/b

15/sin(30)=30=b

and did tangent(30)=15/a

15 * tan(30)= 8.66=a

is this correct?

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- Aug 6th 2010, 11:51 AMgabrielsome one check my trig!!
so there's a right triangle

90 degrees in the bottom left

30 degrees bottom right

15 in length

unknown adjacent

unknown hypotenuse

so i did sin(30) = 15/b

15/sin(30)=30=b

and did tangent(30)=15/a

15 * tan(30)= 8.66=a

is this correct? - Aug 6th 2010, 11:58 AMAckbeet
What is your "15 in length"? What does that correspond to? The length of the side opposite to the 30 degrees? What is b? The hypotenuse? What is a? The side adjacent to the 30 degrees?

- Aug 6th 2010, 12:36 PMArchie Meade
Using tangent, you have 2 ways to find "a"

$\displaystyle tan30^o=\frac{15}{a}$

$\displaystyle \frac{tan30^o}{1}=\frac{15}{a}$

$\displaystyle \frac{1}{tan30^o}=\frac{a}{15}$

Now multiply both sides by 15.

Or....

$\displaystyle tan30^o=\frac{15}{a}$

first multiply both sides by "a"

$\displaystyle atan30^o=\frac{15a}{a}=15$

Finally divide both sides by $\displaystyle tan30^o$ to get "a".

Notice from your diagram that "a" should certainly be longer than 15 units. - Aug 6th 2010, 12:42 PMgabriel
so 15/tan(30) = 25.98 app. 26 is this the final correct answer for a?

- Aug 6th 2010, 12:52 PMArchie Meade