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# How to Solve Side Side Side Triangle Theorem

## How to Solve SSS Triangle Theorem - Formula, Example

##### Definition:

SSS theorem illustrates that, if three sides of a triangle are congruent to three corresponding sides of another triangle, the two triangles are congruent.Given the values of 3 sides (a,b,c) we can calculate the values of three angles (A,B,C).

#### Formula:

##### Example :

Find angle A,B,C from side a=5 ,side b=6 and side c=7

##### Given,

side a = 5 side b = 6 side c = 7

##### To Find,

angle A angle B angle C area perimeter

##### Solution:

Substitute the given values in the respective formula,

###### Step 1:

Let us first find the value of angle A by substituting the values in the formula, A = cos-1(((6 x 6) + (7 x 7) - (5 x 5)) / (2 x 6 x 7)) A = cos-1(.7142) A = 44.4153

##### Step 2:

Now, find the value of angle B. B = cos-1((5 x 5) + (7 x 7) - (6 x 6)) / (2 x 5 x 7)) B = cos-1(.5428) B = 57.1217

###### Find the value of angle C.

C = cos-1((5 x 5) + (6 x 6) - (7 x 7)) / (2 x 5 x 6)) C = cos-1(.2) C = 78.463

###### Step 4:

Find the value of S. S = (5+6+7) / 2 S = 9

###### Substitute the values in the area formula,

Area = 9 x (9-5) x (9-6) x (9-7) Area = 216 Area = 14.6969

###### Step 5:

Now, find the value of perimeter. Perimeter = 5 + 6 + 7 Perimeter = 18