# Cos 30 Degrees | How to Find the value of Cos 30? # Cos 30 Degrees

In trigonometry, the cosine function is defined as the proportion of the adjacent side to the hypotenuse. If the slant of a right triangle is adequate to 30 degrees, and then the measure of cosine at this angle i, the measure of Cos 30 degree is in a divide class as √3/2. It is noted that the value of Sec 30 will be reciprocal of Cos 30 prize .

## Cos 30 Value

Cos 30 degrees is written as carbon monoxide 30° and has a value in fraction form as √3/2 .
Cos 30° = √3/2

Cos 30° = √3/2 is an irrational number and equals to 0.8660254037 ( decimal fraction imprint ) .
consequently, the accurate prize of colorado 30 degrees is written as 0.8660 approx .
√3/2 is the value of Cos 30° which is a trigonometric proportion or trigonometric officiate of a finical angle .

## Cos 30

Another alternative form of Cos 30° is pi/6 or π/6 or cobalt 33 ( ⅓ ) gravitational constant

 Form Formula Value Trigonometric ratio √3 / 2 0.8660254037 Circular system pi/6 or π/6 0.8660254037 Centesimal system Cos 33 (⅓)g 0.8660254037

### Cos 30 Degrees Proof

now that you know the value of Cos 30 degrees, let ’ s explore how to derive this value .
We will study the two approaches to derive it .

1. Theoretical approach
2. Practical approach

Theoretical approach
Knowing the property that distance of an opposite side is one-half of the duration of the hypotenuse – Right triangle property for an lean adequate to 30 degrees in the given right triangle .
As we know two sides those are the length of the opposite side and hypotenuse but the third side is unknown i.e adjacent side. We need to find this side to find the value of Cos 30 degrees . We will use the Pythagorean theorem to find the respect of this third gear side
In triangulum AOB ,
AO 2 = AB2 + AB2
Hypotenuse = d
Opposite side = d/2
d2 = ( d/2 ) 2 + AB2
d2 = d2/4 + AB2
d2 – d2/4 = AB2

( 4d2 – d2 ) /4 = AB2
3d2/4 = AB2
Sqrt ( 3 ) ten d/2 = AB
AB/d = √ ( 3 ) / 2
As d is the duration of the reverse side, so
Length of adjacent / duration of hypotenuse = √3 / 2
The value of angle BOA in the given right triangle is pi/6 and the given ratio as per the definition of cosine proportion represents the value of Cos 30 degrees
Cos 30° =Length of adjacent/length of hypotenuse = √3/2 = 0.8660254037
Practical Approach
Another means to calculate the measure of Cos 30 degree is through a practical approach. sol if we make a good triangle using constructions, Cos pi/6 can be calculated . Step 1 : Mark a point P on the plane and horizontally draw a line on it .
Step 2: With the avail of protractor makes an angle of 300 with the center as P and taking service line as the tie line in footprint 1 .
Step 3: Use the rule to draw a credit line to make an angle of 30 degrees .
Step 4: Using compass draw an arc on the line of angle 30 degrees with any duration. Mark that point as Q .
Step 5: From Q draw a line vertical to the establish ( horizontal line ). Mark it as R ( Intersecting point of the perpendicular line to the base. )
now after drawing a right-angled triangle POQ, we can calculate the value of Cos 30 degrees .
Cos 30° =Length of the adjacent/length of the hypotenuse = OP/OQ .
In the above construction, the distance of the slope OP is taken as 7.5 curium and the length of the adjacent english is unknown. But if we measure it with a rule, It comes out to be 6.5 curium.

Cos 30° = OP/OQ = 6.5/7.5 = 0.866666…
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