Question

cho hình thang abcd có (ab//dc) có b-c=10 tính số đo góc b

Answer 1

\(AB//CD=>\angle\left(B\right)+\angle\left(C\right)=180^0\left(1\right)\)

mà \(\angle\left(B\right)-\angle\left(C\right)=10\left(2\right)\)

(2)\(=>\angle\left(C\right)=\angle\left(B\right)-10\left(3\right)\)

thế(3) vào (1)\(=>2\angle\left(B\right)=190^o\)\(=>\angle\left(B\right)=95^0\)

Answer 2

Ta có: AB//DC(gt)

nên \(\widehat{B}+\widehat{C}=180^0\)(hai góc trong cùng phía)

mà \(\widehat{B}-\widehat{C}=10^0\)(gt)

nên \(\widehat{B}=95^0\)