An isosceles triangle has angle A 30 degrees greater than angle B. Find all angles of triangle?

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pirate67's profile pic

pirate67 | Middle School Teacher | (Level 1) eNoter

Posted on

We know that since we have an isosceles triangle that two of the sides and therefore the angles will be equal. The third angle we are told is 30 degrees more than the one of the others.

Let's call the equal angles' measurement  x

The three angles can be represented by:

x

x

x + 30

 

The three angles will add up to 180:

x + x + x +30 = 180

 

Solving for x:

 

3x + 30 = 180

3x = 150

x = 50

So our 3 angles are 50, 50, 80

 

 

 

 

 

giorgiana1976's profile pic

giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted on

We'll recall the fact that an isosceles triangle has two equal angle. Since the angle A is 30 degrees greater than B, then the equal angles are B and C.

We also know that the sum of the angles in a triangle is of 180 degrees, such as:

A + B + C = 180

A = B + 30

B = C

B + 30 + B + B = 180

3B + 30 = 180

3B = 180 - 30

3B = 150

B = 50 degrees

But B=C=>C=50 degrees.

A = B + 30 = 50+30 = 80 degrees.

Therefore, the requested angles of isosceles triangle ABC are: A=80, B=50, C=50 degrees.

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