ABCD is a rhombus. DPR and CBR are straight lines.
Prove that:
DP.CR=DC.PR
Solution:
DP.CR=DC.PR
Given ABCD is rhombus .
DPR and CBR are straight lines.
∴ AD||CR
we need to Prove : DP.CR=DC.PR
In ∆ ADP and ∆ PCR
We have :
∠ APD = ∠ CPR
∠ ADP = ∠ PRC
∠ DAP = ∠ PCR
∴ ∆ ADP and ∆ PCR are similar triangle .
∴ we can write
AD/DP=CR/PR
Or AD.PR = DP.CR
∴ DC .PR = DP.CR Proved
For two similar triangles [ADP and PCR] which angles are equal. The ratio of sides of one angle can be equal to the ratio of sides of other triangle . Please read about similar triangles , you can get this property. Hope I am able to clarify your query.
How is AD/DP?