ΔABC is similar to ΔPQR. The area of ΔABC is 64 cm², and the area of ΔPQR is 121 cm². If QR = 15.4 cm, what is the length of BC ?

11.2 cm

We have,

ΔABC is similar to ΔPQR

Area of ΔABC = 64 cm²

Area of ΔPQR = 121 cm²

QR = 15.4 cm

According to concept:

\(\frac{ 64}{ 121}\) = \(\frac{ BC^2}{ QR^2}\)

=  \(\frac{ 8}{11}\)=  \(\frac{ BC}{ 15.4}\)

=BC =  \(\frac{ (15.4 × 8)}{ 11}\)

= BC = 11.2 cm