Please help me solve for the angle.

geometry

Steps that I had done to try to solve this problem:

  1. Calculated the third angle for the bigger triangle.
  2. The two angles were identical so, I considered the triangle to be isosceles. (Angle= 80 degrees)
  3. I drew a line parallel to the bottom side of the bigger triangle.
  4. Then a new triangle was formed which was similar to the bigger triangle. I got stuck after that as the ratio of sides did not lead me anywhere.

Just draw an equilateral triangle with its side length equal to the base of the main triangle. enter image description here

Related

Proving function
Determinant of a Pascal Matrix, sort of
Why is the manifold structure on the tangent bundle unique?
Spectrum of composition of convolution and multiplication
Evaluate or simplify $\int\frac{1}{\ln x}\,dx$
Elementary applications of Krein-Milman
Factorial canceling on expansion of binomial coefficients on Concrete Mathematics
Cauchy's Integral Formula and Green's Theorem
Is a Markov process a random dynamic system?
Do probability distributions form a comonad?
Solving a formal power series equation
Consider the sequence defined: $a_1=0, a_{n+1}=3+\sqrt{11+a_n}$, show that is bounded above and increasing using induction.