plz explain the 1 st sum in the lets review which is : in IIgm PQRS , RN is perpendicular to PS and PM  is perpendicular to SR .if PQ = 120 cm , PM =30root5 cm and RN = 180root5 cm , thn what is the measure of the side PS ?  plz answer ...

Given, PQRS is a parallelogram in which RN ⊥ PS and PM ⊥ SR. If PQ = 120 cm , PM = 30√5 cm and RN = 180√5 cm.

In order to find the side PS of the given parallelogram, firstly, we will area of PQRS as:

Area of Parallelogram PQRS = base  × height

= RS × PM  [on considering the base RS, corresponding altitude will be PM]

⇒ Area of PQRS = PQ × PM  [PQ = RS, as opposite sides of a parallelogram are equal]

= 120 × 30√5 cm2  .... (1)

Again, area of Parallelogram PQRS with respect to base  PS and corresponding altitude RN is:

 Area of Parallelogram PQRS = PS  × RN

120 × 30√5 = PS × 180√5   [using (1)]

⇒ PS = 120 × 30√5/180√5  

⇒ PS = 20 cm 

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 first we must find the parallelograms area by multiplying base and height

i.e. 120 * 30root5 = 3600root5

now we know the area is 3600root5

another height is given and the base is PS whose value we are supposed to find so we divide area and height 

i.e. 3600root5 / 180root5 = 20

That is the value of PS .

Hope you found this helpful. :)

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