Find the area of a kite ABCD if BD= 48cm, AB= 25cm, and BC= 26cm?

1 Answer
Jan 4, 2016

#S=408cm^2#

Explanation:

The formula of a kite's area is
#S=(1/2)d1*d2#
where
#d1="kite's long diagonal"#
#d2="kite's short diagonal"#

In the problem, be noticed that once the diagonal BD has an endpoint in B (where 2 segments of different sizes, AB and BD, meet), this diagonal is divided in two equal parts by the other diagonal. Calling E the point where the two diagonals intercept each other, we have:
#BD=2*DE=48# => #DE=24#

In the right triangle ABE we can obtain the segment AE
#AB^2=DE^2+AE^2# => #25^2=24^2+AE^2# => #AE=sqrt(625-576)=sqrt(49)=7#

In the right triangle BCE we can obtain the segment CE
#BC^2=DE^2+CE^2# => #26^2=24^2+CE^2# => #CE=sqrt(676-576)=sqrt(100)=10#

In this way we discovered the previously unknown diagonal:
#AC=AE+CE=7+10=17#

Finally,
#S=(1/2)(d1+d2)=(48+17)/2=408cm^2#