Answer:
Since EF bisects ∠DEF, we know that EF splits ∠DEF in 2 halves from the word 'bisects', which can be written as 'bi- sects' , where bi means 2 and sects means sections
Hence, ∠DEG = ∠GEF --------------(1)
We are given the measure of these angles:
∠DEG = 3x - 4
∠GEF = x + 13
Now, replacing the values in (1):
3x - 4 = x + 13
2x = 17
x = 17/2
Now, finding the measure of ∠DEF:
∠DEF = ∠DEG + ∠GEF
∠DEF = 3x - 4 + x + 13
∠DEF = (51 / 2) - 4 + (17/2) + 13 (x = 17/2)
∠DEF = 34 - 4 + 13
∠DEF = 43°
