Giải thích các bước giải:

a.Ta có: $SA\perp (ABCD)\to SA\perp AB, SA\perp AC, SA\perp AD, SA\perp BC, SA\perp CD, SA\perp BD$

                $AB\perp AD$

$\to AB\perp (SAD)$

b.Vì $ABCD$ là hình vuông $\to AC\perp DB$

        $SA\perp BD$

$\to BD\perp (SAC)$

c.Ta có: $BC\perp AB, SA\perp BC\to BC\perp (SAB)$

d.Ta có: $CD\perp AD, SA\perp CD\to CD\perp (SAD)$

e.Ta có: $BC\perp (SAB)\to BC\perp AH, AH\perp SB$

$\to AH\perp (SBC)$

f.Ta có: $CD\perp (SAD)\to CD\perp AK, AK\perp SD\to AK\perp (SCD)$

g.Ta có: $AH\perp (SBC)\to AH\perp SC$

                $AK\perp (SCD)\to AK\perp SC$

$\to SC\perp (AHK)$