In figure given below abcd is a kite and diagonals intersect at o. If angle dab=112 and angle dcb= 64 . Find angle odd and angle oba
Answers
Answer:
∠ODC = 58° and ∠OBA = 34°
Step-by-step explanation:
We have, ABCD as the given kite. We know that in a kite AD = AB , BC = DC.Also it is given that ∠DAB = 112°; ∠BCD = 64° and diagonals AC and BD intersect each other at O.
Now, in ΔADC and ΔABC, we have
AD = AB (given)
DC = BC (given)
AC = AC (Common)
ΔADC ≅ ΔABC (SSS congruency criterion)
⇒∠OAD = ∠OAB (CPCT) .....(1)
⇒∠OCD = ∠OCB (CPCT) ......(2)
Now, ∠DAB = 112°⇒∠OAD + ∠OAB
= 112°⇒2∠OAD = 112° [using (1)]
⇒∠OAD =56° =∠OAB
Now, ∠BCD = 64°⇒∠OCD + ∠OCB = 64°⇒2∠OCD = 64° [using(2)]⇒
∠OCD = 32° = ∠OCB
We know that diagonals of a kite intersect each other at right angle, so ∠AOB = ∠BOC = ∠COD = ∠DOA = 90°
Now, in ΔDOC, we have∠ODC + ∠COD + ∠OCD = 180° [Angle sum property of triangle]
⇒∠ODC + 90° + 32° = 180°⇒∠ODC = 180° − (90° + 32°)
= 180° − 122° = 58°
In ΔAOB, we have∠OBA + ∠AOB + ∠OAB = 180° [Angle sum property of triangle]
⇒∠OBA + 90° + 56° = 180°⇒∠OBA
= 180° − (90°+56°) = 34°
So, ∠ODC = 58° and ∠OBA = 34°
PLEASE MARK THIS AS THE BRAINLIEST ANSWER...............
Since, EBC is an equilateral triangle, we have
EB = BC = EC … (i)
Also, ABCD is a square
So, AB = BC = CD = AD … (ii)
From (i) and (ii), we get
EB = EC = AB = BC = CD = AD … (iii)
Now, in ∆ECD
∠ECD = ∠BCD + ∠ECB
= 90o + 60o
= 150o … (iv)
Also, EC = CD [From (iii)]
So, ∠DEC = ∠CDE … (v)
∠ECD + ∠DEC + ∠CDE = 180o [Angles sum property of a triangle]
150o + ∠DEC + ∠DEC = 180o [Using (iv) and (v)]
2 ∠DEC = 180o – 150o = 30o
∠DEC = 30o/2
∠DEC = 15o … (vi)
Now, ∠BEC = 60o [BEC is an equilateral triangle]
∠BED + ∠DEC = 60o
xo + 15o = 60o [From (vi)]
x = 60o – 15o
x = 45o
Hence, the value of x is 45o.
(b) Given, ABCD is a rectangle
∠ECD = 146o
As ACE is a straight line, we have
146o + ∠ACD = 180o [Linear pair]
∠ACD = 180o – 146o = 34o … (i)
And, ∠CAB = ∠ACD [Alternate angles] … (ii)
From (i) and (ii), we have
∠CAB = 34o ⇒ ∠OAB = 34o … (iii)
In ∆AOB
AO = OB [Diagonals of a rectangle are equal and bisect each other]
∠OAB = ∠OBA … (iv) [Equal sides have equal angles opposite to them]
From (iii) and (iv),
∠OBA = 34o … (v)
Now,
∠AOB + ∠OBA + ∠OAB = 180o
∠AOB + 34o + 34o = 180o [Using (3) and (5)]
∠AOB + 68o = 180o
∠AOB = 180o – 68o = 112o
Hence, ∠AOB = 112o, ∠OAB = 34o and ∠OBA = 34o
(c) Here, ABCD is a rhombus and diagonals intersect at O and ∠OAB : ∠OBA = 3 : 2
Let ∠OAB = 2xo
Then,
∠OBA = 2xo
We know that diagonals of rhombus intersect at right angle,
So, ∠OAB = 90o
Now, in ∆AOB
∠OAB + ∠OBA = 180o
90o + 3xo + 2xo = 180o
90o + 5xo = 180o
5xo = 180o – 90o = 90o
xo = 90o/5 = 18o
Hence,
∠OAB = 3xo = 3 x 18o = 54o
OBA = 2xo = 2 x 18o = 36o and
∠AOB = 90o