Question

If in AABC, ZB =90", AB = 12 cm and BC- 5cm then the value of cosc is​

Answer 1

Answer:

△ABCis a right angled triangle

AC

2

=BC

2

+AB

2

AC

2

=(5)

2

+(12)

2

AC

2

=25+144

AC

2

=169=(13)

2

or AC=13

Now from figure,

i.cosA=

AC

AB

=

13

12

ii.cscA=

BC

AC

=

5

13

iii.cosC=

AC

BC

=

13

5

iv.cscC=

AB

AC

=

12

13

Hence, proved.

solution

Answer 2

Answer:





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Class 10

>>Maths

>>Introduction to Trigonometry

>>Trigonometric Identities

>>In a ABC angle B = 90 degree, AB = 12

Question



In a △ABC angle B = 90 degree, AB = 12 cm and BC = 5 cm 

Find (i) cos A (ii) cosec A (iii) cos C (iv) cosec C 

Medium

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Solution



Verified by Toppr

From figure: △ABCis a right angled triangle

AC2=BC2+AB2

AC2=(5)2+(12)2

AC2=25+144

AC2=169=(13)2

 or AC=13

 Now from figure,

 i.cosA=ACAB=1312

 ii.cscA=BCAC=513

 iii.cosC=ACBC=135

 iv.cscC=ABAC=1213

 Hence, proved.