A rhombus of side 20cm has two angles of 60 each .Find the length of diagonals
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The length of one diagonal = 2 *20cos(60)= 20 cm
The length of the other diagonal = 2 *20sin(60) = 20sqrt(3) cm
The length of the other diagonal = 2 *20sin(60) = 20sqrt(3) cm
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✒ ʟᴇᴛ ᴀʙᴄᴅ ʙᴇ ᴀ ʀʜᴏᴍʙᴜs ᴏғ sɪᴅᴇ 20 ᴄᴍ. ᴀɴᴅ ᴀɴɢʟᴇ ʙᴀᴅ = ᴀɴɢʟᴇ ʙᴄᴅ = 60°
ɴᴏᴛᴇ ᴛʜᴀᴛ ᴛʜᴇ ᴅɪᴀɢᴏɴᴀʟs ᴏғ ᴀ ʀʜᴏᴍʙᴜs ᴀʀᴇ ᴘᴇʀᴘᴇɴᴅɪᴄᴜʟᴀʀ ʙɪsᴇᴄᴛᴏʀs ᴏғ ᴀɴɢʟᴇ ʙᴀᴅ ᴀɴᴅ ᴀɴɢʟᴇ ᴀʙᴄ ʀᴇsᴘᴇᴄᴛɪᴠᴇʟʏ.
sᴏ, ∆ ᴀᴏʙ ɪs ᴀ ʀɪɢʜᴛ ᴛʀɪᴀɴɢʟᴇ sᴜᴄʜ ᴛʜᴀᴛ ᴀɴɢʟᴇ ʙᴀᴏ = 30°, ᴀɴɢʟᴇ ᴀᴏʙ = 90° ᴀɴᴅ ᴀʙ= 20 ᴄᴍ.
ᴛʜᴇʀᴇғᴏʀᴇ,
ᴄᴏs ᴀɴɢʟᴇ ʙᴀᴏ = ᴏᴀ/ᴀʙ
=> ᴄᴏs 30° = ᴏᴀ/20
=> √3/2 = ᴏᴀ/20
=> ᴏᴀ = √3/2 × 20 = 10√3
ᴀʟsᴏ,
sɪɴ ᴀɴɢʟᴇ ʙᴀᴏ = ᴏʙ/ᴀʙ
=> sɪɴ 30° = ʙᴏ/20
=> 1/2 = ʙᴏ/20
=> ʙᴏ = 20/2 = 10
ᴛʜᴇʀᴇғᴏʀᴇ,
✴ ᴀᴄ= 2
✴ ᴀᴏ= 2 × 10√3 = 20√3 ᴄᴍ,
✴ ʙᴅ= 2
✴ ʙᴏ = 2 × 10 = 20 ᴄᴍ.
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