body a,
body button,
body [type='button'],
body input[type='reset'],
body input[type='submit'],
body [role="button"],
::-webkit-search-cancel-button,
::-webkit-search-decoration,
::-webkit-scrollbar-button,
::-webkit-file-upload-button,
body .sweezy-custom-cursor-hover {
cursor: url("data:image/png;base64,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") 6 3, pointer !important;
}
html,
body,
body select,
body .sweezy-custom-cursor-default-hover {
cursor: url("data:image/png;base64,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") 1 1, auto !important;
}
6:
Gọi chiều dài là x
=>Chiều rộng là 3/4x
Theo đề, ta có: 3/4x^2=300
=>x=20
=>Chiều rộng là 15m
Chu vi là (20+15)*2=70(m)