What do you mean by (C.P.C.T)????

Dear student,

 

CPCT stands for corresponding parts of congruent triangles.

It means that if two triangles are congruent with any of SAS, ASA, SSS and RHS congruence rules then remaining angles and sides corresponding in both triangles are equal.

 

Example:

 

 

Given: ABCD is a parallelogram. E is the mid point of BC. AB is produced to L.

To prove: (i) ∆DEC ≅ ∆LBE

(ii) CD = BL, DE = EL

Proof: In ∆DCE and ∆LBE

∠DEC = ∠LEB (Vertically opposite angles)

CE = BE (E is the mid point of BC)

∠DCE = ∠EBL (Pair of alternate angles since AB||CD)

∴ ∆DEC ≅ ∆LBE (ASA Congruence Criterion)

CD = BL (c.p.c.t)

DE = EL (c.p.c.t)

 

Regards