If, at the close of the hearing, the board of supervisors determines to annex the territory, or any portion thereof, it shall so declare by resolution. The annexation shall be effective upon the date of the adoption of the resolution unless one percent or more of the voters living within the territory to be annexed have at or prior to hearing filed written objections to the annexation. If written objections to the proposed annexation are made by the number of voters specified in this section, the annexation shall not be effective until it is approved by a majority vote of the voters of the territory proposed to be annexed. The election shall be conducted substantially as provided in Sections 1179, 1180, and 1181.