can anyone answer thisthree questions at a time please.....I'll mark u as brain list
Answers
Answer:
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21)
Take ∆ADC and ∆ABC:
AC = AC (common side)
AD = BC (opposite sides of a parallelogram are equal)
angle CAD = angle CAB (given)
Hence by SAS congruency, ∆ADC and ∆ABC are congruent.
By CPCT property, angle DCA = angle BCA.
Hence the diagonal bisects angle C.
22)
Given: x + y = w + z
Now, x = angle AOC, y = angle COB
Now, clearly x + y + w + z = 360⁰ (together they form a complete angle)
--> x + y + (x + y) = 360⁰
--> 2(x + y) = 360⁰
--> x + y = 180⁰
Hence, angle AOC + angle COB = 180⁰
Therefore, AOB is a straight line
23)
i) Consider ∆ABD and ∆BAC
AD = BC (given)
angle DAB = angle CBA (given)
AB = AB (common side)
Therefore by SAS congruency, ∆ABD and ∆BAC are congruent
ii) Now since ∆ABD is congruent to ∆BAC, therefore by CPCT, BD = AC
Hope that you will find this useful :)
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