Consider the non-right triangle below. Suppose that m∠BCA=71∘, and that x=31 cm and y=50 cm. What is the degree measure of ∠ABC?
m∠ABC=
​

m<ABC = 71°

Step-by-step explanation:

Given:

m<BCA = 71°

x = 31 cm

y = 50 cm

Required:

m<ABC

Solution:

First, find AB, using Cosine Rule:

AB² = x² + y² - 2xy*Cos m<ABC

Plug in the values

AB² = 31² + 50² - 2(31)(50)*cos 71

AB² = 3,461 - 1,009.26128

AB² = 2,451.73872

AB = √2,451.73872

AB = 49.5150353 ≈ 50 cm

✔️Since AB ≈ 50 cm, and AC is also 50 cm, it means the triangle is an isosceles triangle.

Therefore, the base angles of ∆ABC, <ABC and <BCA, would be congruent.

Therefore,

m<BCA = m<ABC = 71°

m<ABC = 71°

answer: add the !

step-by-step explanation: then we will answer

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.