First drop down is 180°, second drop down is 1 and 4, third drop down is 1.
Solution:
Data in the given image:
2, 3 and 4 are interior angles of the triangle.
1 is the exterior angle of the triangle.
Triangle sum property:
Sum of the interior angles of the triangle are supplementary.
By the triangle sum property,
The sum of the measures of angles 2, 3 and 4 is supplementary (180°).
m∠2 + m∠3 + m∠4 = 180° – – – (1)
The sum of the measures of angles 4 and 1 is 180°.
Because they form a linear pair.
m∠1 + m∠4 = 180° – – – (2)
Using the substitution property, equate (1) and (2).
m∠2 + m∠3 + m∠4 = m∠1 + m∠4
Then by the property of equality, subtract m∠4 on both sides, we get
m∠2 + m∠3 + m∠4 – m∠4 = m∠1 + m∠4 – m∠4
m∠2 + m∠3 = m∠1
Hence first drop down is 180°, second drop down is 1 and 4, third drop down is 1.