Question

Vă rooog! Ofer coroniță!​

Answer 1

Răspuns:

Explicație pas cu pas:

Din Δ dreptunghic ADB    tg ∡B/2=AD/AB=15/25=3/5

tg2x=2tgx/(1-tg²x)    ⇒tg ∡B=2×3/5/(1-9/25)=6/5×25/16=15/8

in Δ dreptunghic CEB   tg∡B=CE/EB      CE=AD=15

15/8=15/EB        EB=8cm

BC ²=AD²+EB²=225+64=289     BC=17 cm

CD=AB-EB=25-8=17 cm                  

Pabcd=AB+BC+CD+AD=25+17+17+15=40+36=76 cm

Aabcd=(25+17) 15/2=42×15/2=21×15=315 cm²