Calculation: We know 3, 4 and 5 are Pythagorean triplets. If Sin A = 3/5 then Cos A = 4/5. Cot A = Cos A/Sin A. â (4/5)/ (3/5) = 4/3. Again 5, 12, 13 are Pythagorean triplets. If Cos B = 5/13 then Sin B = 12/13. Cot B = Cos B/Sin B. â (5/13)/ (12/13) = 5/12.
The correct option is D-1665Explanation for the correct 1 Find the value of cosA,sinBGiven that, sinA=45and cosB= know that, sin2Ăž+cos2Ăž=1cosA=1-sin2A=1-452=35Now the value of sinBis negative because B lies in 3rd quadrant. sinB=1-12132=1-144169=25169=-513Step 2 Find the value of cosA+BWe know that, cosA+B= option D is correct.
Step by step video & image solution for If A,B are acute angles and sinA = 3/5, cosB =12/13 then find cos(A+B) by Maths experts to help you in doubts & scoring excellent marks in Class 12 exams. Class 12 MATHS QUESTION BANK. If sin A = 4 5 and cos B = 5 13,where 0 < A <
/ FĂłrmulas / MatemĂĄtica / 1. RelaçÔes trigonomĂ©tricas fundamentais $\mathrm{sen}^{2} a + \cos^{2} a = 1$ $tg a = \frac{sen a}{\cos a}$ $cotg a = \frac{\cos a }{sen a}$ $sec a = \frac{1}{\cos a}$ $cossec a = \frac{1}{sen a}$ 2. RelaçÔes trigonomĂ©tricas derivadas $tg^{2} a + 1 = sec^{2} a$ $cotg^{2} a +1 = cossec^{2} a$ 3. Seno da soma - Cosseno da soma - Tangente da soma $sena+b = sena \ . \cos b + senb \ . \cosa$ $\cos a+b = \cos a \ . \cos b - sena \ . senb$ $tga+b = \frac{tga + tgb}{1-tga \ . tgb}$ 4. Seno da diferença - Cosseno da diferença - Tangente da diferença $sena-b = sena \ . \cos b - senb \ . \cos a$ $\cos a-b = \cos a \ . \cos b + sena \ . senb$ $tga-b = \frac{tga - tgb}{1+tga \ . tgb}$ 5. Soma de senos - Soma de cossenos - Soma de tangentes $sen a + sen b = 2 sen \left \frac{a+b}{2} \right \ . \cos \left \frac{a-b}{2} \right$ $ \cos a+ \cos b = 2 \cos \left\frac{a+b}{2} \right \ . \cos \left\frac{a-b}{2}\right$ $tg a + tg b = \left \frac{sen a+b}{\cos a \ . \cos b} \right$ 6. Subtração de senos - Subtração de cossenos - Subtração de tangentes $ sen a - sen b = 2 sen \left \frac{a-b}{2} \right \ . \cos \left \frac{a+b}{2} \right $ $ \cos a - \cos b = -2 sen \left \frac{a+b}{2} \right \ . sen \left \frac{a-b}{2} \right$ $tg a -tg b = \left \frac{sen a-b}{\cos a \ . \cos b} \right $ 7. Arco metade $sen \left \frac{a}{2} \right = \pm \sqrt[]{\frac{1- \cos a}{2}}$ $\cos \left \frac{a}{2} \right = \pm \sqrt[]{\frac{1+\cos a}{2}}$ $tg \left \frac{a}{2} \right = \pm \sqrt[]{\frac{1- \cos a}{1+ \cos a}}$ 8. Arco duplo $sen2a = 2sena \ . \cos a$ $\cos 2a = \cos^{2} a - sen^{2}a$ $tg2a = \frac{2tga}{1-tg^{\style{font-familyArial; font-size31px;}{2}}a}$ 9. Arco triplo $sen3a = 3sena-4sen^{3}a$ $\cos 3a = 4 \cos^{3} 3a - 3 \cos a$ $tg 3a = \frac{3tg a-tg^{3}a}{1-3tg^{\style{font-familyArial; font-size30px;}2}a}$ 10. Arco quĂĄdruplo $sen4a =4sena \ . \cos a -8sen^{3} a \ . \cos a $ $\cos 4a = 8 \cos^{4} a - 8 \cos^{2} a +1$ $tg 4a = \frac{4tg a- 4tg^{3}a}{1-6tg^{\style{font-familyArial; font-size30px;}2}a+tg^{\style{font-familyArial; font-size30px;}4} a}$ 11. Arco quĂntuplo $sen5a = 5sena - 20sen^{3} a +16sen^{5} a$ $\cos 5a = 16 \cos^{5} a - 20 \cos^{3} a +5 \cos a$ $tg 5a = \frac{tg^{5}a - 10tg^{3}a +5tg a}{1-10tg^{\style{font-familyArial; font-size30px;}2}a+5tg^{\style{font-familyArial; font-size30px;}4} a}$ 12. Identidade par/Ămpar $sen -a = -sena$ $\cos -a = \cos a$ $tg-a = -tga$ $cossec-a = -cosseca$ $sec-a = sec a$ $cotg -a = -cotg a$ 13. Arcos complementares $sen 90° \hspace{ -a = \cos a$ $\cos 90° \hspace{ -a = sen a$ $tg 90° \hspace{ -a = cotg a$ $cotg 90° \hspace{ -a = tg a$ $sec 90° \hspace{ -a = cossec a$ $cossec 90° \hspace{ -a = sec a$ 14. Periodicidade $sen 360° \hspace{ +a = sen a$ $\cos 360° \hspace{ +a = \cos a$ $tg 180° \hspace{ +a = tga$ $cotg 180° \hspace{ +a = cotga$ $sec 360° \hspace{ +a = seca$ $cossec 360° \hspace{ +a = cosseca$ 15. Transformação de produto para soma $sen a \ . sen b = \frac { \cos a-b - \cosa+b}{2}$ $\cos a \ . \cos b = \frac {\cos a-b + \cos a+b}{2}$ $sen a \ . \cos b = \frac {sen a-b+sen a+b}{2}$ $tg a \ . tgb = \frac {tg a + tgb}{cotga + cotgb}$ $cotga \ . cotgb = \frac {cotga + cotgb}{tg a + tg b}$ $tga \ . cotgb = \frac {tg a + cotg b}{cotg a + tg b}$ 16. PotĂȘncias de seno e cosseno $sen^{2} a = \frac{1-cos 2a}{2}$ $sen^{3} a = \frac{3sen a -sen3a}{4}$ $sen^{4} a = \frac{\cos 4a -4 \cos 2a + 3}{8}$ $sen^{5} a = \frac{10sen a -5 sen 3a + sen5a}{16}$ $sen^{6} a = \frac{10 - 15 \cos 2a +6 \cos 4a -cos 6a}{32}$ $\cos^{2} a = \frac{1+ \cos 2a}{2}$ $\cos^{3} a = \frac{3 \cos a +cos3a}{4}$ $\cos^{4} a = \frac{\cos 4a +4 \cos 2a + 3}{8}$ $\cos^{5} a = \frac{10 \cos a +5 sen 3a + \cos 5a}{16}$ $\cos^{6} a = \frac{10 + 15 \cos 2a +6 \cos 4a + cos 6a}{32}$ ï»ż
Shortcuts & Tips. Click heređto get an answer to your question ïž In a Î ABC, cos A = 3/5 and cos B = 5/13. The value of cos C can be.
Given as sin A = 4/5 and cos B = 5/13 As we know that cos A = â1 â sin2 A and sin B = â1 â cos2 B, where 0 < A, B < Ï/2 Therefore let us find the value of sin A and cos B cos A = â1 â sin2 A = â1 â 4/52 = â1 â 16/25 = â25 â 16/25 = â9/25 = 3/5 sin B = â1 â cos2 B = â1 â 5/132 = â1 â 25/169 = â169 â 25/169 = â144/169 = 12/13 i sin A + B As we know that sin A +B = sin A cos B + cos A sin B Therefore, sin A + B = sin A cos B + cos A sin B = 4/5 Ă 5/13 + 3/5 Ă 12/13 = 20/65 + 36/65 = 20 + 36/65 = 56/65 ii cos A + B As we know that cos A +B = cos A cos B â sin A sin B Therefore, cos A + B = cos A cos B â sin A sin B = 3/5 Ă 5/13 â 4/5 Ă 12/13 = 15/65 â 48/65 = -33/65 iii sin A â B As we know that sin A â B = sin A cos B â cos A sin B Therefore, sin A â B = sin A cos B â cos A sin B = 4/5 Ă 5/13 â 3/5 Ă 12/13 = 20/65 â 36/65 = -16/65 iv cos A â B As we know that cos A - B = cos A cos B + sin A sin B Therefore, cos A - B = cos A cos B + sin A sin B = 3/5 Ă 5/13 + 4/5 Ă 12/13 = 15/65 + 48/65 = 63/65
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