asked 213k views
3 votes
Find x, AB, BC, AC if △ABC is isosceles with AB = BC.

asked
User KBIIX
by
7.7k points

1 Answer

2 votes

Explanation:

Since we are not given the required parameters, we can use the following parameters

Given:

∠ A = 5 x + 30 °

∠ B = 2 x

Since △ABC is isosceles with AB = BC, then ∠ A = ∠ C (the base angles of an isosceles triangle are equal)

Since sum of angle in a triangle are the same, then;

∠ A + ∠ B + ∠ C = 180°

Substitute the given functions and get x;

5x+30 + 2x + 5x+30 = 180

12x + 60 = 180

12x = 180-60

12x = 120

x = 120/12

x = 10°

∠ A = 5x+30

∠ A = 5(10)+30

∠ A = 80°

Since ∠ A =∠ C

∠ C = 80°

For ∠ B;

∠ B = 2x

∠ B = 2(10)

∠ B = 20°

Let AB = 1, since AB = BC, BC = 1

To get AC, use the sin rule;

a/sin∠ A = b/sin∠ B

a/sin80 = 1/sin20

asin20 = sin80

a = sin80/sin20

a = 0.9848/0.3420

a = 2.879

Hence AC ≈ 3

Note that the values of the sides and angles are assumed.

answered
User Alex Iceman
by
8.4k points

No related questions found

Welcome to Qamnty — a place to ask, share, and grow together. Join our community and get real answers from real people.