By: Sarchia Khursheed (سەرچیا خورشید)

1. 1
Soran University
Faculty of Engineering - Civil Engineering Department
ANGLE
DETERMINATION
Student: Sarchia Khursheed
Group: 2nd
Date: 26.04.2016
Supervisor: Eng. Anwar Jabbar

2. 2
Introduction
Just like regular numbers, angles can be added to obtain a sum,
perhaps for the purpose of determining the measure of an unknown
angle. Sometimes we can determine a missing angle because we know
that the sum must be a certain value. The sum of
the degree measures of angles in any triangle
equals 180 degrees.
In right hand there is a picture of triangle ABC,
where angle A = 60 degrees, angle B = 50 degrees
and angle C = 70 degrees.
If we add all three angles in any triangle we get
180 degrees. So, the measure of angle A + angle B
+ angle C = 180 degrees. This is true for any triangle in the world of
geometry. We can use this idea to find the measure of angle(s) where
the degree measure is missing or not given.
We have another rule for measuring angles when we have the
dimensions of the triangle which called the Law of Cosines (also called
the Cosine Rule) which is very useful for solving triangles: c2 = a2 + b2
– 2ab cos θ
Objective
To determine the angles of a triangle with known distances of sides.
Equipment
 Measuring Tape or Wheel Measuring Roller
 Steel Rods
 Rope
 Hammer
Procedure
1. Select four points on the ground, install a steel rod at each
point.
2. Connecting all the points by a thin rope, also connect points
diagonally.
3. Take all dimensions between points by measuring tape.

3. 3
4. By connecting points diagonally we getting two triangles, we
can obtain the angles of triangles by cosine rule.
Data and Calculation
c2 = a2 + b2 – 2ab cos θ => cos θ =
𝑎2+𝑏2− 𝑐2
2𝑎𝑏
θ1 : 103.73o
θ2 : 80.16o
θ3 : 100.94o
θ4 : 76.05o
Result and Conclusion
In conclusion we know that by knowing the distances of triangle’s
slides we can obtain the desired angle. We use this method to
determine the angles of a parallelogram. We divide the parallelogram
into two triangles by creating two diagonal lines, and then using cosine
law for obtaining each angles, and finally we take sum of all angles
and it must be 360o.