由a/sin75º=2/sin15º
a/(sin45cos30+cos45sin30)=2/(sin45cos30-cos45sin30)
a/(√6/4+√2/4)=2/(√6/4-√2/4)
a=4+2√3,
c²=2²+(4+2√3)²
c²=32+16√3
c=√(24+2√24×8+8)
=√24+√8
=2√6+2√2.
由a/sin75º=2/sin15º
a/(sin45cos30+cos45sin30)=2/(sin45cos30-cos45sin30)
a/(√6/4+√2/4)=2/(√6/4-√2/4)
a=4+2√3,
c²=2²+(4+2√3)²
c²=32+16√3
c=√(24+2√24×8+8)
=√24+√8
=2√6+2√2.