Question

please solve this asap :(​

Answer 1

Answer:

3rd one

can't solve but i can just ....

Answer 2

✪ᴀɴsᴡᴇʀ✪

• 1) $\frac{4} {5}$

★ᴇxᴘʟᴀɪɴᴀᴛɪᴏɴ★

$⇒\cos(2 \tan^{ - 1} ( \frac{1}{5} )+ \cos^{ - 1} ( { \frac{63}{65} } ) )$

$⇒\cos( \tan^{ - 1} ( \frac{ 2.\frac{1}{5} }{1 - { (\frac{1}{5} )}^{2} } )+ \cos^{ - 1} ( { \frac{63}{65} } ) )$

$⇒\cos( \tan^{ - 1} ( \frac{2 \times 5}{25 - 1} )+ \cos^{ - 1} ( { \frac{63}{65} } ) )$

$⇒\cos(\tan^{ - 1} ( \frac{10}{24} )+ \cos^{ - 1} ( { \frac{63}{65} } ) )$

$⇒\cos(\tan^{ - 1} ( \frac{5}{12} )+ \cos^{ - 1} ( { \frac{63}{65} } ) )$

$⇒\cos(\cos^{ - 1} ( \frac{12}{ \sqrt{ {5}^{2} + {12}^{2} } } )+ \cos^{ - 1} ( { \frac{63}{65} } ) )$

$⇒\cos(\cos^{ - 1} ( \frac{12}{13} )+ \cos^{ - 1} ( { \frac{63}{65} } ) )$

$⇒\cos(\cos^{ - 1} ( \frac{12}{13} ))cos( \cos^{ - 1} ( { \frac{63}{65} } )) - \sin(\cos^{ - 1} ( \frac{12}{13} ))sin( \cos^{ - 1} ( { \frac{63}{65} } ))$

$⇒ \frac{12}{13}.\frac{63}{65} - \sqrt{1 - {( \frac{12}{13} )}^{2} }\sqrt{1 - {( \frac{63}{65} )}^{2} }$

$⇒ \frac{12}{13}.\frac{63}{65} - \sqrt{( \frac{13^{2} - 12^{2} }{13^{2} } )}\sqrt{(\frac{65^{2} - 63^{2} }{65^{2} } )}$

$⇒ \frac{12}{13}.\frac{63}{65} - \sqrt{ \frac{25}{13^{2} } } \sqrt{ \frac{256}{65^{2} } }$

$⇒ \frac{12}{13}.\frac{63}{65} - \frac{5}{13}.\frac{16}{65}$

$⇒ \frac{12 \times 63 - 5 \times 16}{13 \times 65} = \frac{676}{13 \times 65}$

$⇒ \frac{676}{13 \times 65} = \frac{13 \times 13 \times 4}{13 \times 13 \times 5}$

$⇒ \frac{4}{5}$