ABCD is a trapezium in which AB II CD and
AD = BC (see Fig. 8.23). Show that
(i) ZA= ZB
(ii) ZC= ZD
(iii) A ABCEA BAD
D
(iv) diagonal AC = diagonal BD
Answers
Answer:
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(I) Since, AE// DC and CE// DA
Therefore AECD is a parallogram.
→ AD = CE
→ But AD = BC [ given]
CE = BC
<CBR = <E
Since , ABE is a straight line,
<ABC + <CBE = 180°
→ <ABC + <E = 180° —1
Since, AD//EC and AE is transversal
<ABC + <E = 180⁰. —2 [cointerior angles]
<ABC + <E = <A + <E [From 1 and 2]
<ABC = <A ie. <B = <A
hence Proved .
(ii) AB is parallel to DC
→ <A + <D = 180° and <B + <C = 180⁰ [Co-interior]
→ <A + <D = <B + <C
→ <D = <C [ As, <A = <B]
Hence Proved
(iii) In triangle ABC and Triangle BAD
1. AB = AB [COMMON]
2. AD = BC [ITS GIVEN]
3. <BAD = <ABC
Therefore ABC ≈ BAD [ By S.A.S.]
Hence Proved
(iv) Since, Triangle ABC ≈ Triangle BAD
→ AC = BD
ie. diagonal AC = diagnal BD
Hence Proved