Side AD of parallelogram ABCD is 12 cm, diagonal BD is perpendicular to AB, BD = 7 cm. Find the angles of a parallelogram.

Since the diagonal BD is perpendicular to the side AB, the triangle ABD is rectangular.

Then SinBAD = BD / AD = 7/12.

Angle BAD = arcsin (7/12) ≈ arcsin (0.583) ≈ 35.7.

The sum of the adjacent angles of the parallelogram is 180, then the angle ABC = 180 – BAD = 180 – 35.7 = 144.3.

In a parallelogram, the opposite angles are equal, then the angle BCD = ABD = 35.7, the angle ADC = ABC = 144.3.

Answer: The angles of the parallelogram are 35.7 and 144.3.




One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.

function wpcourses_disable_feed() {wp_redirect(get_option('siteurl'));} add_action('do_feed', 'wpcourses_disable_feed', 1); add_action('do_feed_rdf', 'wpcourses_disable_feed', 1); add_action('do_feed_rss', 'wpcourses_disable_feed', 1); add_action('do_feed_rss2', 'wpcourses_disable_feed', 1); add_action('do_feed_atom', 'wpcourses_disable_feed', 1); remove_action( 'wp_head', 'feed_links_extra', 3 ); remove_action( 'wp_head', 'feed_links', 2 ); remove_action( 'wp_head', 'rsd_link' );