Prove angle 1 being congruent to angle 4

we know the two triangles are congruent because BD = BD. Also, AD = CD because it is bisecting AC. Since these triangles are congruent, we know that congruent parts of congruent triangles are congruent, so angle 1 is congruent to angle 4.

hope it you

step-by-step explanation:

sin(7pi/6 - pi/3)  

= sin(7pi/6 - 2pi/6)  

= sin(5pi/6)  

= sin(pi - pi/6)  

= sin(pi/6)  

= 1/2  

sin 7pi/6 - sin pi/3  

= sin (pi + pi/6) - sin pi/3  

= -sin pi/6 - sin pi/3  

= -1/2 - sqrt(3)/2  

= -(1+sqrt(3))2