document.write( "Question 459618: in a parallelogram ABCD the diagonal AC is at right angle to AB if AB =12CM and BC =13 CM find the area of the parallelogram\r \n" );
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document.write( "given diagonal AC is at right angle to AB i.e.triangle ABC is a right angled triangle \n" );
document.write( "now applying Pythagorean theorem \n" );
document.write( "BC^2=AC^2+AB^2 \n" );
document.write( "given AB=12 cm and AC=13 cm \n" );
document.write( "hence AC^2=BC^2-AB^2 \n" );
document.write( "AC^2=169-144=25 \n" );
document.write( "therefore AC=5 cm \n" );
document.write( "now area of parallelogram ABCD=2*area of triangle ABC \n" );
document.write( "since we know that area of right angle triangle=1/2 *base *altitude \n" );
document.write( "so area of triangle ABC=1/2*12*5=30 sq cm \n" );
document.write( "and hence area of parallelogram is 60 sq cm \n" );
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