Angle A of an isoceles triangle ABC measures 20 degrees more than three times angle B. Find the measure of angle C.

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justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

In an isosceles triangle two angles are equal. The measure of angle A is 20 degrees more than three times angle B. Angle B has the same measure as angle C.

The sum of the three angles is 180 degrees. If the measure of angle C is X.

X + X + 3*X + 20 = 180

=> 5X = 160

=> X = 32

The measure of angle C is 32 degrees.

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najm1947 | Elementary School Teacher | (Level 1) Valedictorian

Posted on

Sum of 3 angles of a triangle = 180 degrees

In isoceles triangle base angles are equal

i.e. M angle B = M angle C = x, say 

Let y be the M angle A, the vetrex angle

y+2x = 180, sum of three angles ..........(1)

and y is 20 dgrees more than three times Measure angle B

i.e. y = 20+3x 

substituting value of y in (1) we get

20+3x+2x = 180

3x+2x = 180-20

5x = 160

x = 160/5 = 32 dgrees

Measure angle C = 32 degrees

 

 

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