Three angles of a triangle are in an arithmetic progression. If the largest angle
is 75 , find the remaining angles.
with method please
Answers
Solution;
Let us assume the three angles to be: (a-d), a, (a+d).
It is given that largest angle of the triangle is 75°
According to our assumption, the largest angle is (a+d).
Therefore (a+d) = 75°
Now we know that, according to Angle Sum Property of a triangle, the sum of all the interior angles is equal to 180°. This implies:
→ a - d + a + a + d = 180°
→ 3a = 180°
→ a = 180°/3 = 60°
Now based on our assumption we get:
→ a + d = 75°
→ 60° + d = 75°
→ d = 75° - 60° = 15°
Therefore substituting the values in our assumptions we get:
- a - d ⇒ 60° - 15° = 45°
- a ⇒ 60°
- a + d ⇒ 75°
Therefore the remaining angles are 45° and 60°
Given ,
- The three angles of triangle are in AP
- The largest angle is 75
Let , the three angles of triangle are (a - d) , a , and (a + d)
We know that ,
The sum of all angles of triangle is 180
Thus ,
a - d + a + a + d = 180
3a = 180
a = 180/3
a = 60
Since , the largest angle is 75
Thus ,
a + d = 75
60 + d = 75 { because , a = 60 }
d = 75 - 60
d = 15
Hence , the three angles are 45 , 60 and 75
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