feng8180
幼苗
共回答了17个问题采纳率:88.2% 举报
⑴在RTΔADC1中,AC1=√(AD^2-CD^2)=7.5;
⑵①由ΔD1C1P≌ΔDC1A知:PC1=AC1=7.5,
SΔD1C1P=1/2×7.5×10=37.5,
又SΔD11P=1/2×12.5×C1E,∴C1E=6,
∴C1F=10-6=4;
②D1E=√(D1C1^2-C1E^2)=6
D1P=12.5,∴PE=12.5-6=6.5
∴AE=BF=X+6.5,
∴BC1^2=BF^2+C1F^2=58.25,
又BP^2=AB^2+AP^2=100+X^2
ⅰ)当∠BPC1=90°时,
BC1^2=BP^2+PC1^2,即58.25=100+X^2+56.25,X^2=-98,无解.
ⅱ)当∠BC1P=90°时,
58.25+56.25=100+X^2,X=√14.5≈3.81.
∴当X=3.81时,ΔBC1P是直角三角形.
1年前
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