From previous exercises, we know that the measure of ∠ 3 is 50^(∘)
According to the Exterior Angle Theorem, the measure of an exterior angle of a triangle is equal to the sum of the measures of the two nonadjacent interior angles. We see that ∠ 6 is exterior angle to ∠ 3. Therefore, we can equate it's measure with the sum of the two nonadjacent angles, 50^(∘) and 90^(∘).
m∠ 6=90^(∘)+50^(∘).
By simplifying the equation, we can find the measure of ∠ 6.