Objectives:Develop and use formulas for the sums of the measures of interior and exterior angles of polygons
3.7 Midsegments of Triangles & Trapezoids
Warm-Up:Seven & eleven are both odd numbers. Your task is to make them both even without performing a mathematical operation.
711
a segment whose endpoints are the midpoints of the two sides
Mid-segment of a Triangle:
If a segment joins the midpoints of two sides of a triangle, then the segment is parallel to the third side, and is half its length.
Triangle Mid-Segment Conjecture:
In triangle DEF, A, B, and C are midpoints. Name pairs of parallel segments.
Find DE
Find AB
D and E are midpoints.Find the measure of <A.
In Triangle EFG, H, J, and K are midpoints. Find HJ, JK, and FG.
Given DE, DF, and FE are the lengths of mid-segments. Find the perimeter of triangle ABC.
Find DE
Mid-segment of a Trapezoid:
a segment whose endpoints are the midpoints of the non-parallel sides
Trapezoid Mid-Segment Conjecture:
A midsegment of a trapezoid is PARALLEL to the bases of the trapezoid and has a measure equal to the average of the base lengths.
Find NO
Find PQ
Find KL
Find KL
Find DE, FG, & HI
Find AB & CD
Find AB, WO, & CD