Answer:
The true statements are:
m∠ 3 + m∠ 4 = 180° ⇒ 1st
m∠ 2 + m∠ 4 + m∠ 6 = 180° ⇒ 2nd
m∠ 2 + m∠ 4 = m∠ 5 ⇒ 3rd
Explanation:
* Look to the attached diagram to answer the question
# m∠ 3 + m∠ 4 = 180°
∵ ∠ 3 and ∠ 4 formed a straight angle
∵ The measure of the straight angle is 180°
∴ m∠ 3 + m∠ 4 = 180° ⇒ true
# m∠ 2 + m∠ 4 + m∠ 6 = 180°
∵ ∠ 2 , ∠ 4 , ∠ 6 are the interior angles of the triangle
∵ The sum of the measures of interior angles of any Δ is 180°
∴ m∠ 2 + m∠ 4 + m∠ 6 = 180° ⇒ true
# m∠ 2 + m∠ 4 = m∠ 5
∵ In any Δ, the measure of the exterior angle at one vertex of the
triangle equals the sum of the measures of the opposite interior
angles of this vertex
∵ ∠ 5 is the exterior angle of the vertex of ∠ 6
∵ ∠2 and ∠ 4 are the opposite interior angles to ∠ 6
∴ m∠ 2 + m∠ 4 = m∠ 5 ⇒ true
# m∠1 + m∠2 = 90°
∵ ∠ 1 and ∠ 2 formed a straight angle
∵ The measure of the straight angle is 180°
∴ m∠1 + m∠2 = 90° ⇒ Not true
# m∠4 + m∠6 = m∠2
∵ ∠ 4 , ∠ 6 , ∠ 2 are the interior angles of a triangle
∵ There is no given about their measures
∴ We can not says that the sum of the measures of ∠ 4 and ∠ 6 is
equal to the measure of ∠ 2
∴ m∠4 + m∠6 = m∠2 ⇒ Not true
# m∠2 + m∠6 = m∠5
∵ ∠ 5 is the exterior angle at the vertex of ∠ 6
∴ m∠ 2 + m∠ 6 = m∠ 5 ⇒ Not true