|  |  | GEO0007 -- Midpoint Theorem

## GEO0007 -- Midpoint Theorem

##### The Theorem Statement [Nar04]

Theorem. [Midpoint Theorem] Let ABC be a triangle, and let Al and Bl be the midpoints of BC and AC respectively. Then the line AlBl is parallel to the base AB.

##### The Image - GCLC 5.0

##### Prover's Code

    point A 20 10
    point B 70 10
    point C 35 40

    drawsegment A B
    drawsegment A C
    drawsegment B C

    midpoint B_l B C
    midpoint A_l A C

    drawsegment A_l B_l

    cmark_b A
    cmark_b B
    cmark_t C

    cmark_lt A_l
    cmark_rt B_l

    prove { equal { signed_area3 A_l B_l A } { signed_area3 A_l B_l B } }

##### Proved -- Proof, made with GCLC, v1.0

proofGEO0007.pdf

|  |  | GEO0007 -- Midpoint Theorem